The 2004 United States Senate election in Florida took place on November 2, 2004, alongside other elections to the United States Senate in other states, elections to the United States House of Representatives, and various state and local elections. Democratic incumbent Bob Graham ran unsuccessfully for president of the United States instead of seeking a fourth term. Mel Martínez won the open race to succeed Graham over Betty Castor.

Primary elections were held on August 31, 2004. Castor defeated U.S. representative Peter Deutsch to win the Democratic nomination, while Martínez won the Republican nomination over 2000 nominee Bill McCollum and businessman Doug Gallagher with the support of President George W. Bush.

In the general election, Martínez won the open seat with 49.4 percent of the vote to 48.3 percent for Castor. This was the first open election for this seat since 1974 and the closest race of the 2004 United States Senate elections. As of 2026, this is the last election in which an incumbent senator opted not to run for re-election in Florida.

Democratic primary

Candidates Betty Castor, former president of the University of South Florida, former education commissioner of Florida, and former state senator Peter Deutsch, U.S. representative from Broward County Bernard Klein, businessman Alex Penelas, mayor of Miami-Dade County

Declined Bob Graham, incumbent U.S. senator since 1987 and former governor

Results

Republican primary Candidates Johnnie Byrd, state representative from Plant City and speaker of the Florida House of Representatives Doug Gallagher, businessman Larry Klayman, attorney William Kogut Sonya March Mel Martínez, former U.S. secretary of Housing and Urban Development and candidate for lieutenant governor in 1994 Bill McCollum, former U.S. representative from Longwood and nominee for U.S. Senate in 2000 Karen Saull

Withdrew Mark Foley, U.S. representative from Jupiter (withdrew September 6, 2003) Daniel Webster, state senator from Clermont Dave Weldon, U.S. representative from Indialantic

Campaign An early contender for the Republican nomination was U.S. Representative Mark Foley, who raised $3 million for his Senate campaign and was seen as marginally more moderate than his opponents. However, longstanding rumors regarding Foley's sexuality came under scrutiny in the alternative press.Michelangelo Signorile, “Liberace Candidate: Mark Foley’s glass closet” , New York Press, May 28, 2003.2004 “Outed Hill staffer condemns campaign: Mikulski and Foley become newest congressional targets as FMA vote nears” , Washington Blade (District of Columbia), July 9, 2004."Being gay in the GOP: Congressman Mark Foley: A model of political hypocrisy and personal cowardice" , Boston Phoenix, May 30, 2003Mark Meenan, “Is He Gay or Not? U.S. Rep. Mark Foley calls press to say he won't talk about his sexual preference” , Gay City News, May 30, 2003. While Foley denounced the rumors in an unusual press conference, he did not deny them, instead arguing that his sexuality had no bearing on his ability as a legislator. Foley withdrew from the campaign on September 6, 2003, citing his father's diagnosis with cancer. Foley would later resign from office in 2006 and come out as "a gay man" after revelations that he had sent explicit sexual messages to teenage boys who had served as congressional pages.

Martínez was supported by the Bush administration.

Results

General election

Candidates Dennis Bradley, activist (Veterans) Betty Castor, former president of the University of South Florida, former education commissioner of Florida, and former state senator (Democratic) Mel Martínez, former U.S. secretary of Housing and Urban Development and candidate for lieutenant governor in 1994 (Republican)

Predictions Source Ranking As of Sabato's Crystal Ball November 1, 2004

Polling Poll source Date(s)administered Samplesize Margin BettyCastor (D) MelMartínez (R) Other UndecidedReuters/Zogby InternationalOctober 29 – November 1, 2004601 (LV)± 4.1%43%48%1%9%FOX News/Opinion DynamicsOctober 30–31, 2004700 (LV)± 3.0%47%41%–12%SurveyUSAOctober 29–31, 2004738 (LV)± 3.7%48%48%4%–Strategic Vision (R)October 29–31, 2004801 (LV)± 3.0%45%49%–6%InsiderAdvantageOctober 29–31, 2004400 (LV)± 5.0%47%46%1%7%Reuters/Zogby InternationalOctober 28–31, 2004600 (LV)± 4.0%46%46%–7%CNN/USA Today/GallupOctober 28–31, 20041,138 (LV)± 4.0%48%46%–5%1,300 (RV)± 3.0%48%45%–7%Quinnipiac UniversityOctober 27–31, 20041,098 (LV)± 3.0%44%49%–6%Reuters/Zogby InternationalOctober 27–30, 2004600 (LV)± 4.1%48%45%2%5%Reuters/Zogby InternationalOctober 26–29, 2004601 (LV)± 4.1%47%46%2%5%Reuters/Zogby InternationalOctober 25–28, 2004601 (LV)± 4.1%45%47%2%6%Mason-DixonOctober 26–27, 2004625 (LV)± 4.0%46%47%–6%Strategic Vision (R)October 25–27, 2004801 (LV)± 3.0%46%49%–5%Reuters/Zogby InternationalOctober 24–27, 2004601 (LV)± 4.1%45%45%1%9%The New York TimesOctober 23–27, 2004802 (LV)± 3.0%47%44%–10%Reuters/Zogby InternationalOctober 23–26, 2004601 (LV)± 4.1%48%45%–7%Quinnipiac UniversityOctober 22–26, 2004944 (LV)± 3.2%46%49%–5%Reuters/Zogby InternationalOctober 22–25, 2004601 (LV)± 4.1%47%47%–6%Strategic Vision (R)October 22–24, 2004801 (LV)± 3.0%46%48%–6%InsiderAdvantageOctober 22–24, 2004400 (LV)± 5.0%44%46%–10%SurveyUSAOctober 22–24, 2004738 (LV)± 3.7%50%47%3%–Reuters/Zogby InternationalOctober 21–24, 2004601 (LV)± 4.1%44%47%1%8%Schroth, Eldon & Associates (D)/The Polling Company (R)October 19–21, 2004800 (LV)± 3.5%44%44%–12%Research 2000October 18–21, 2004600 (LV)± 4.0%48%48%–4%Strategic Vision (R)October 18–20, 2004801 (LV)± 3.0%45%48%–7%Quinnipiac UniversityOctober 15–19, 2004808 (LV)± 3.5%47%47%–5%1,208 (RV)± 2.8%41%43%1%15%SurveyUSAOctober 15–17, 2004596 (LV)± 4.1%47%49%3%1%Mason-DixonOctober 14–16, 2004625 (LV)± 4.0%45%45%1%9%University of North FloridaOctober 10–15, 2004614 (LV)± 4.0%38%35%4%23%Strategic Vision (R)October 12–14, 2004801 (LV)± 3.0%47%47%–6%Strategic Vision (R)October 4–6, 2004801 (LV)± 3.0%48%45%–7%Mason-DixonOctober 4–5, 2004625 (LV)± 4.0%41%46%1%12%Quinnipiac UniversityOctober 1–5, 2004717 (LV)± 3.7%47%48%–5%1,083 (RV)± 3.0%44%40%2%14%SurveyUSAOctober 1–3, 2004706 (LV)± 3.8%46%50%3%1%CNN/USA Today/GallupSeptember 18–22, 2004674 (LV)± 4.0%51%45%–4%843 (RV)49%43%–8%Quinnipiac UniversitySeptember 18–21, 2004819 (RV)± 3.4%43%42%1%14%SurveyUSASeptember 12–14, 2004602 (LV)± 4.1%49%45%5%1%Rasmussen ReportsAugust 24, 2004500 (LV)± 4.5%44%44%–12%

Betty Castor vs. Bill McCollum Poll source Date(s)administered Samplesize Margin BettyCastor (D) BillMcCollum (R) Other UndecidedRasmussen ReportsAugust 24, 2004500 (LV)± 4.5%42%39%–19%

Peter Deutsch vs. Mel Martínez Poll source Date(s)administered Samplesize Margin PeterDeutsch (D) MelMartínez (R) Other UndecidedRasmussen ReportsAugust 24, 2004500 (LV)± 4.5%39%47%–14%

Peter Deutsch vs. Bill McCollum Poll source Date(s)administered Samplesize Margin PeterDeutsch (D) BillMcCollum (R) Other UndecidedRasmussen ReportsAugust 24, 2004500 (LV)± 4.5%37%44%–19%

Endorsements

Results

Results by county +2004 United States Senate election in Florida (by county)CountyMel Martínez RepublicanBetty Castor DemocraticVarious Candidates Other partiesMarginTotal votes cast# %# %# %# %Alachua43,07439.63%63,80958.71%1,8021.65% -20,735 -19.08%108,685Baker6,81569.16%2,85328.95%1861.89%3,96240.21%9,854Bay49,63967.63%22,19030.23%1,5642.13%27,44937.40%73,393Bradford6,53460.83%3,93836.66%2702.51%3,59624.17%10,742Brevard142,39454.44%111,47742.62%7,6822.94%30,91711.82%261,553Broward231,26633.63%442,72864.37%13,7802.00% -211,462 -30.74%687,774Calhoun3,13353.70%2,52643.30%1753.00%60710.40%5,834Charlotte43,07955.48%32,83742.29%1,7292.23%10,24213.19%77,645Citrus33,99849.68%31,69946.32%2,7424.01%2,2993.36%68,439Clay58,13172.24%20,83125.89%1,5031.86%37,30046.35%80,465Collier81,94865.97%40,33232.47%1,9341.56%41,61633.50%124,214Columbia14,01457.15%9,78039.89%7262.96%4,23417.26%24,520DeSoto4,99453.58%4,03143.25%2953.17%96310.33%9,320Dixie3,32252.67%2,73543.36%2503.97%5879.31%6,307Duval205,00154.68%163,74843.68%6,1601.64%41,25311.00%374,909Escambia88,78763.56%48,27434.56%2,6321.88%40,51329.00%139,693Flagler18,29448.13%18,81249.49%9042.38% -518 -1.36%38,010Franklin2,70647.13%2,88650.26%1502.61% -180 -3.13%5,742Gadsden5,23025.15%15,24673.33%3161.52% -10,016 -48.18%20,792Gilchrist4,06058.87%2,57837.38%2583.74%1,48221.49%6,896Glades2,14752.15%1,82144.23%1493.62%3267.92%4,117Gulf4,08657.36%2,85840.12%1802.53%1,22817.24%7,124Hamilton2,20644.75%2,59752.68%1272.58% -391 -7.93%4,930Hardee4,02456.38%2,80639.32%3074.30%1,21817.06%7,137Hendry5,35055.75%4,02741.97%2192.28%1,32313.78%9,596Hernando36,55746.08%39,63449.96%3,1433.96% -3,077 -3.88%79,334Highlands22,32654.72%17,19642.15%1,2783.13%5,13012.57%40,800Hillsborough207,33146.29%230,29851.42%10,2612.29% -22,967 -5.13%447,890Holmes5,11463.42%2,60832.34%3424.24%2,50631.08%8,064Indian River34,33857.82%23,51139.59%1,5432.60%10,82718.23%59,392Jackson10,44953.73%8,60544.24%3952.04%1,8449.49%19,449Jefferson2,72236.93%4,50461.10%1451.97% -1,782 -24.17%7,371Lafayette1,76854.57%1,39042.90%822.53%37811.67%3,240Lake68,42556.37%49,63540.89%3,3192.73%18,79015.48%121,379Lee139,81059.90%89,04838.15%4,5311.94%50,76221.75%233,389Leon45,45334.09%86,18064.64%1,6911.27% -40,727 -30.55%133,324Levy8,73553.39%7,12943.57%4973.04%1,6069.82%16,361Liberty1,44848.75%1,45949.12%632.12% -11 -0.37%2,970Madison3,31840.58%4,64056.74%2192.68% -1,322 -16.16%8,177Manatee72,82951.53%64,79545.85%3,6992.62%8,0345.68%141,323Marion73,53053.23%60,81444.02%3,7992.75%12,7169.21%138,143Martin39,07655.41%29,86842.35%1,5792.23%9,20813.06%70,523Miami-Dade367,86749.21%366,48249.02%13,2021.77%1,3850.19%747,551Monroe18,07547.19%18,96149.50%1,2673.31% -886 -2.31%38,303Nassau21,89368.40%9,51929.74%5951.86%12,37438.66%32,007Okaloosa65,14674.71%19,64522.53%2,4132.77%45,50152.18%87,204Okeechobee5,95950.00%5,46445.84%4964.16%4954.16%11,919Orange188,12149.15%187,54949.00%7,0811.85%5720.15%382,751Osceola42,10352.00%36,56945.16%2,2962.84%5,5346.84%80,968Palm Beach200,44237.96%318,04260.23%9,5661.81% -117,600 -22.27%528,050Pasco89,40048.01%90,76148.74%6,0443.24% -1,361 -0.73%186,205Pinellas197,64042.55%254,45154.78%12,3792.66% -56,811 -12.23%464,470Polk108,77452.28%93,23144.81%6,0512.91%15,5437.47%208,056Putnam15,94152.23%13,70144.89%8762.87%2,2407.34%30,518St. Johns56,25166.19%27,31932.14%1,4201.67%28,93234.05%84,990St. Lucie44,43645.34%50,66051.69%2,9052.96% -6,224 -6.35%98,001Santa Rosa49,14974.65%15,16523.03%1,5242.31%33,98451.62%65,838Sarasota95,42550.08%91,65148.10%3,4551.81%3,7741.98%190,531Seminole102,89856.11%76,57941.76%3,9142.13%26,31914.35%183,391Sumter17,92957.05%12,84440.87%6562.09%5,08516.18%31,429Suwannee9,09558.45%6,06939.00%3972.55%2,62919.45%15,561Taylor4,24150.17%3,97246.98%2412.85%2693.19%8,454Union2,87462.49%1,63235.49%932.05%1,24227.00%4,599Volusia104,03246.21%114,93251.05%6,1742.74% -10,900 -4.84%225,138Wakulla5,24045.10%6,04852.05%3312.85% -808 -6.95%11,619Walton16,03868.56%6,77028.94%5852.50%9,26839.62%23,393Washington6,41463.45%3,45234.15%2422.39%2,96229.30%10,108Totals3,672,86449.43%3,590,20148.32%166,8292.24%82,6631.11%7,429,894

Counties that flipped from Democratic to Republican Calhoun (largest city: Blountstown) Citrus (largest city: Homosassa Springs) Dixie (largest city: Cross City) Glades (largest city: Moore Haven) Gulf (largest city: Port St. Joe) Levy (largest city: Williston) Putnam (largest city: Palatka) Taylor (largest city: Perry) Jackson (largest city: Marianna) Lafayette (largest city: Mayo) Union (largest city: Lake Butler) Washington (largest city: Chipley) Brevard (largest municipality: Palm Bay) Okeechobee (largest municipality: Okeechobee) Polk (largest municipality: Lakeland) Miami-Dade (largest city: Miami) Osceola (largest municipality: Kissimmee) Orange (largest city: Orlando) Escambia (largest city: Pensacola) Hendry (largest city: Clewiston) Marion (largest city: Ocala)