The United States Senate career of Hillary Rodham Clinton began when she defeated Republican Rick Lazio in the 2000 United States Senate election in New York. She was elected to a second term in 2006. Clinton resigned from the Senate on January 21, 2009, to become United States Secretary of State for the Obama Administration.

Clinton was first elected to the U.S. Senate in 2000, becoming the first female senator from New York and the first First Lady to simultaneously hold elected office. As a senator, she chaired the Senate Democratic Steering and Outreach Committee from 2003 to 2007. She advocated for medical benefits for September 11 first responders. She supported the resolution authorizing the Iraq War in 2002, but opposed the surge of U.S. troops in 2007. Clinton ran for president in 2008, but lost to Barack Obama in the Democratic primaries. She resigned from the Senate to become Obama's secretary of state in 2009.

First term

Upon entering the United States Senate, Clinton maintained a low public profile while building relationships with senators from both parties, to avoid the polarizing celebrity she experienced as First Lady (it was reported that when Elizabeth Dole joined the Senate in 2003 under somewhat similar circumstances, she modeled her initial approach after Clinton's, (preview only) as did the nationally visible Barack Obama in 2005). Clinton also forged alliances with religiously inclined senators by becoming a regular participant in the Senate Prayer Breakfast., p. 548.

Following the September 11, 2001 attacks, Clinton sought to obtain funding for the recovery efforts in New York City and security improvements in her state. Working with New York's senior senator, Charles Schumer, she was instrumental in quickly securing $21.4 billion in funding for the World Trade Center site's redevelopment.Bernstein, A Woman In Charge, p. 548. Not a favorite of New York City police officers and firefighters who were in attendance, she was audibly booed and heckled at The Concert for New York City on October 20, 2001, although her husband was loudly applauded. Causes included the lack of support from the police and firefighter unions during her 2000 campaign, and her inattentive, possibly disrespectful behavior during Bush's September 20 address to Congress. Hillary Clinton said she did not take the booing personally: "They can blow off steam any way they want to. They've earned it." She subsequently took a leading role in investigating the health issues faced by 9/11 first responders, eventually earning the praise and endorsement of New York City's Uniformed Fire Officers Association and the Uniformed Firefighters Association for her 2006 re-election bid. In 2005, Clinton issued two studies that examined the disbursement of federal homeland security funds to local communities and first responders. Clinton voted for the USA Patriot Act in October 2001. In 2005, when the act was up for renewal, she worked to address some of the civil liberties concerns with it, before voting in favor of a compromise renewed act in March 2006 that gained large majority support.

Clinton strongly supported the 2001 U.S. military action in Afghanistan, saying it was a chance to combat terrorism while improving the lives of Afghan women who suffered under the Taliban government. Clinton voted in favor of the October 2002 Iraq War Resolution, which authorized United States President George W. Bush to use military force against Iraq, should such action be required to enforce a United Nations Security Council Resolution after pursuing with diplomatic efforts (however, Clinton voted against the Levin Amendment to the Resolution, which would have required the President to conduct vigorous diplomacy at the U.N., and would have also required a separate Congressional authorization to unilaterally invade Iraq. She did vote for the Byrd Amendment to the Resolution, which would have limited the Congressional authorization to one year increments, but the only mechanism necessary for the President to renew his mandate without any Congressional oversight was to claim that the Iraq War was vital to national security each year the authorization required renewal). Clinton later said that she did not read the full classified National Intelligence Estimate that was delivered ten days before the vote to all members of Congress, and that gave a more subtle case for Iraq possessing weapons of mass destruction than the Bush Administration's abridged summary, but that she was briefed on the report.

After the Iraq War began, Clinton made trips to both Iraq and Afghanistan to visit American troops stationed there, such as the 10th Mountain Division based in Fort Drum, New York. In spring 2004, Clinton publicly castigated U.S. Deputy Secretary of Defense Paul Wolfowitz at a hearing, saying his credibility was gone due to false predictions he had made before the war's start. p. 385. On a visit to Iraq in February 2005, Clinton noted that the insurgency had failed to disrupt the democratic elections held earlier, and that parts of the country were functioning well. Noting that war deployments were draining regular and reserve forces, she co-introduced legislation to increase the size of the regular United States Army by 80,000 soldiers to ease the strain. (no longer free) In late 2005, Clinton said that while immediate withdrawal from Iraq would be a mistake, Bush's pledge to stay "until the job is done" was also misguided, as it would give Iraqis "an open-ended invitation not to take care of themselves". She criticized the administration for making poor decisions in the war, but added that it was more important to solve the problems in Iraq. This centrist and somewhat vague stance caused frustration among those in the Democratic party who favored immediate withdrawal.

During her time as senator, Clinton supported retaining and improving health benefits for veterans. She lobbied against the closure of several military bases in New York, including Fort Drum, and visited almost all military installations within the state. She formed strong working relationships with several high-ranking military officers, including General Franklin L. "Buster" Hagenbeck at Fort Drum, who was Commander of the 10th Mountain Division, and General Jack Keane, who was Vice Chief of Staff of the Army. When in 2003 the opportunity opened to take a seat on the Senate Foreign Relations Committee or the Senate Armed Services Committee, she chose the latter, even though past New York senators such as Daniel Patrick Moynihan and Jacob Javits had traditionally been highly visible on the former. Once on the Armed Services Committee, she made a practice of going to every meeting, no matter how obscure the topic. In the words of New York Times reporter Mark Landler, Clinton became "a military wonk"; in part this was to bolster her credentials should she stage a run for president.

Senator Clinton voted against the two major tax cuts packages introduced by President Bush, the Economic Growth and Tax Relief Reconciliation Act of 2001 and the Jobs and Growth Tax Relief Reconciliation Act of 2003, saying it was fiscally irresponsible to reopen the budget deficit. At the 2000 Democratic National Convention, Clinton had called for maintaining a budget surplus to pay down the national debt for future generations. At a fundraiser in 2004, she told a crowd of financial donors that "Many of you are well enough off that ... the tax cuts may have helped you" but that "We're saying that for America to get back on track, we're probably going to cut that short and not give it to you. We're going to take things away from you on behalf of the common good."

In Clinton's first term as senator, New York's jobless rate rose by 0.7 percent after a nationwide recession. The state's manufacturing sector was especially beleaguered, losing about 170,000 jobs. In 2005, Clinton and Senator Lindsey Graham cosponsored the American Manufacturing Trade Action Coalition, which provides incentives and rewards for completely domestic American manufacturing companies. In 2003, Clinton convinced the information technology firm Tata Consultancy Services to open an office in Buffalo, New York, but some criticized the plan because Tata is also involved in the business of outsourcing. (no longer free) In 2004, Clinton co-founded and became the co-chair of the Senate India Caucus with the aid of USINPAC, a political action committee. In 2005, Clinton voted against ratification of the Central America Free Trade Agreement, believing that it did not provide adequate environmental or labor standards. In this she differed with her husband, who supported CAFTA; the ratification was successful.

Senator Clinton led a bipartisan effort to bring broadband access to rural communities. She cosponsored the 21st Century Nanotechnology Research and Development Act, which encourages research and development in the field of nanotechnology. She included language in an energy bill to provide tax exempt bonding authority for environmentally-conscious construction projects, and introduced an amendment that funds job creation to repair, renovate and modernize public schools.

In 2005, Clinton was joined by former House Speaker Newt Gingrich, who once led the Republican opposition to her husband's administration, in support of a proposal for incremental universal health care. She also worked with Bill Frist, the Republican Senate Majority Leader, in support of modernizing medical records with computer technology to reduce human errors, such as misreading prescriptions.

During the 2005 debate over the use of filibusters by Senate Democrats, which prevented some of President Bush's judicial nominations from being confirmed, Clinton was not part of the "Gang of 14", a bipartisan group of senators who would support cloture but oppose the Republican threat to abolish the filibuster. However, she did vote in favor of cloture along with that group, thereby allowing the nominations to come to a vote. She subsequently voted against three of the nominees, but all were confirmed by the Senate. Clinton voted against the confirmation of John Roberts as Chief Justice of the United States, saying "I do not believe that the Judge has presented his views with enough clarity and specificity for me to in good conscience cast a vote on his behalf", but then said she hoped her concerns would prove to be unfounded. Roberts was confirmed by a solid majority, with half the Senate's Democrats voting for him and half against. She joined with about half of the Democratic Senators in support of the filibuster against the nomination of Samuel Alito to the United States Supreme Court, and subsequently voted against his confirmation along with almost all Democratic members of the Senate. On the Senate floor, Clinton said Alito would "roll back decades of progress and roll over when confronted with an administration too willing to flaunt [sic] the rules and looking for a rubber stamp". Alito was confirmed in a vote split largely along party lines.

Clinton sought to establish an independent, bipartisan panel patterned after the 9/11 Commission, an independent commission chaired by former New Jersey governor Thomas Kean, that was charged with investigating the September 11 attacks, to investigate the response to Hurricane Katrina by the federal, state and local governments, but could not obtain the two-thirds majority needed to overcome procedural hurdles in the Senate.

In 2005, Clinton called for the Federal Trade Commission to investigate how hidden sex scenes showed up in the controversial video game Grand Theft Auto: San Andreas. Along with Senators Joe Lieberman and Evan Bayh, she introduced the Family Entertainment Protection Act, intended to protect children from inappropriate content found in video games. Similar bills have been filed in some states such as Michigan and Illinois, but were ruled to be unconstitutional.