
| State | Date | Romney | Santorum | Gingrich | Paul | Spread | |
| Total | - | 9,809,662 | 3,909,460 | 2,720,135 | 2,063,043 | Romney +5,900,202 | |
| Iowa | Jan 3 | 29,805 | 29,839 | 16,163 | 26,036 | Santorum +34 | |
| New Hampshire | Jan 10 | 97,591 | 23,432 | 23,421 | 56,872 | Romney +40,719 | |
| South Carolina | Jan 21 | 168,123 | 102,475 | 244,065 | 78,360 | Gingrich +75,942 | |
| Florida | Jan 31 | 776,159 | 223,249 | 534,121 | 117,461 | Romney +242,038 | |
| Nevada | Feb 4 | 16,486 | 3,277 | 6,956 | 6,175 | Romney +9,530 | |
| Missouri | Feb 7 | 63,882 | 139,272 | 0 | 30,647 | Santorum +75,390 | |
| Minnesota | Feb 7 | 8,240 | 21,988 | 5,263 | 13,282 | Santorum +8,706 | |
| Colorado | Feb 7 | 23,012 | 26,614 | 8,445 | 7,759 | Santorum +3,602 | |
| Maine | Feb 11 | 2,373 | 1,136 | 405 | 2,258 | Romney +115 | |
| Michigan | Feb 28 | 409,899 | 377,521 | 65,016 | 115,712 | Romney +32,378 | |
| Arizona | Feb 28 | 239,167 | 138,031 | 81,748 | 43,952 | Romney +101,136 | |
| Wyoming | Feb 29 | 822 | 673 | 165 | 439 | Romney +149 | |
| Washington | Mar 3 | 19,111 | 12,089 | 5,221 | 12,594 | Romney +6,517 | |
| Georgia | Mar 6 | 233,611 | 176,259 | 425,395 | 59,100 | Gingrich +191,784 | |
| Ohio | Mar 6 | 456,205 | 445,697 | 175,375 | 111,093 | Romney +10,508 | |
| Tennessee | Mar 6 | 154,911 | 205,012 | 132,072 | 49,801 | Santorum +50,101 | |
| Virginia | Mar 6 | 158,119 | 0 | 0 | 107,451 | Romney +50,668 | |
| Oklahoma | Mar 6 | 80,356 | 96,849 | 78,730 | 27,596 | Santorum +16,493 | |
| Massachusetts | Mar 6 | 265,110 | 44,255 | 16,990 | 35,037 | Romney +220,855 | |
| Idaho | Mar 6 | 27,514 | 8,115 | 940 | 8,086 | Romney +19,399 | |
| North Dakota | Mar 6 | 2,691 | 4,510 | 962 | 3,186 | Santorum +1,324 | |
| Alaska | Mar 6 | 4,285 | 3,860 | 1,865 | 3,175 | Romney +425 | |
| Vermont | Mar 6 | 23,965 | 14,273 | 4,944 | 15,369 | Romney +8,596 | |
| Kansas | Mar 10 | 6,250 | 15,290 | 4,298 | 3,767 | Santorum +9,040 | |
| Guam | Mar 10 | 215 | 0 | 0 | 0 | Romney +215 | |
| Virgin Islands | Mar 10 | 101 | 23 | 18 | 112 | Paul +11 | |
| Northern Marianas | Mar 10 | 740 | 53 | 28 | 27 | Romney +687 | |
| Alabama | Mar 13 | 180,250 | 214,545 | 182,197 | 30,892 | Santorum +32,348 | |
| Mississippi | Mar 13 | 88,715 | 94,981 | 90,409 | 12,749 | Santorum +4,572 | |
| Hawaii | Mar 13 | 4,548 | 2,589 | 1,116 | 1,975 | Romney +1,959 | |
| Puerto Rico | Mar 18 | 106,431 | 10,574 | 2,702 | 1,595 | Romney +95,857 | |
| Illinois | Mar 20 | 430,535 | 322,831 | 73,362 | 85,872 | Romney +107,704 | |
| Louisiana | Mar 24 | 49,758 | 91,321 | 29,656 | 11,467 | Santorum +41,563 | |
| Wisconsin | Apr 3 | 346,279 | 289,648 | 45,944 | 87,896 | Romney +56,631 | |
| Maryland | Apr 3 | 117,527 | 69,020 | 26,088 | 22,698 | Romney +48,507 | |
| District of Columbia | Apr 3 | 3,122 | 0 | 477 | 535 | Romney +2,587 | |
| New York | Apr 24 | 103,142 | 14,181 | 20,720 | 24,947 | Romney +78,195 | |
| Pennsylvania | Apr 24 | 464,062 | 146,745 | 83,795 | 105,356 | Romney +317,317 | |
| Connecticut | Apr 24 | 40,265 | 4,078 | 6,135 | 8,014 | Romney +32,251 | |
| Rhode Island | Apr 24 | 9,156 | 823 | 878 | 3,462 | Romney +5,694 | |
| Delaware | Apr 24 | 16,143 | 1,690 | 7,741 | 3,017 | Romney +8,402 | |
| North Carolina | May 8 | 634,902 | 100,690 | 73,867 | 107,109 | Romney +527,793 | |
| Indiana | May 8 | 413,657 | 85,255 | 41,087 | 99,628 | Romney +314,029 | |
| West Virginia | May 8 | 77,477 | 13,408 | 6,986 | 12,263 | Romney +64,069 | |
| Nebraska | May 15 | 129,548 | 25,537 | 9,523 | 18,199 | Romney +104,011 | |
| Oregon | May 15 | 200,365 | 26,457 | 15,173 | 35,889 | Romney +164,476 | |
| Kentucky | May 22 | 117,599 | 15,654 | 10,445 | 22,044 | Romney +95,555 | |
| Arkansas | May 22 | 103,164 | 20,137 | 7,448 | 20,267 | Romney +82,897 | |
| Texas | May 29 | 995,946 | 114,973 | 67,888 | 172,466 | Romney +823,480 | |
| California | Jun 5 | 1,320,954 | 87,233 | 62,203 | 169,055 | Romney +1,151,899 | |
| New Jersey | Jun 5 | 184,732 | 11,892 | 7,094 | 23,612 | Romney +161,120 | |
| South Dakota | Jun 5 | 34,033 | 5,916 | 2,074 | 6,704 | Romney +27,329 | |
| Montana | Jun 5 | 95,690 | 12,482 | 6,080 | 20,119 | Romney +75,571 | |
| New Mexico | Jun 5 | 67,310 | 9,660 | 5,367 | 9,482 | Romney +57,650 | |
| Utah | Jun 26 | 205,609 | 3,348 | 1,074 | 10,384 | Romney +195,225 |