Mitt Romney, the former governor of Massachusetts and the runner-up in the 2008 primaries, had been preparing to run for president ever since the 2008 election,[5] and was from early on the favorite to win the nomination.

It was the first presidential primary to be affected by a Supreme Court ruling that allowed unlimited independent expenditures to support or oppose candidates through super PACs.

Santorum won Kansas and three Southern primaries, but was unable to make any significant gains on Romney, who maintained a solid lead over all other contenders after securing more than half of the delegates allocated in the month of March.

Gingrich followed suit on May 2, after the Republican National Committee (RNC) declared Romney the presumptive nominee on April 25 and put its resources behind him.

On May 14, Paul announced that he would suspend funding the remaining primary contests and devote his resources to winning delegates at state conventions.

Romney chose congressman Paul Ryan to be his running mate, but they went on to lose the general election to incumbent President Barack Obama.

Mitt Romney Detroit, Michigan, U.S. Massachusetts On May 14, 2012, Paul announced that he would no longer actively campaign in states that have not held primaries, but rather focus on a strategy to secure delegates before the convention.

Leading up to the convention, Ron Paul won bound pluralities of the official delegations from the states of Iowa, Louisiana, Maine, Minnesota, Nevada, and Oregon (but not the Virgin Islands, despite winning the popular vote there).

Due to disputes these were reduced to Iowa, Minnesota, and Nevada; however, he additionally had nomination-from-the-floor-pluralities in the states of Oregon and Alaska, plus the Virgin Islands.

The change was made to prolong the race, giving lesser known candidates a chance and making it harder for a frontrunner to secure the majority early.

The same day that the Ames Straw Poll was being held, Texas Governor Rick Perry was drafted by strong national Republican support.

In November, as Herman Cain's campaign was stumbling, former Speaker of the House Newt Gingrich rose in the polls and asserted himself as the fourth major opponent to Romney.

[25] But in the weeks before the Iowa caucus, Gingrich's new-found lead began to quickly evaporate as super PACs sympathetic to Mitt Romney and others spent over $4.4 million in negative advertising targeting the former Speaker.

[29] On the eve of the January 3, 2012 Iowa Caucus, the first real contest of the primary season, Paul, Santorum and Romney were all viewed as possible winners.

[32][33] Newt Gingrich said after Iowa that his positive campaign had been a weakness, and had allowed his rivals to gain the upper hand through negative attacks paid by super PACs supporting them.

[35] Jon Huntsman Jr., a moderate, had staked his candidacy on New Hampshire and invested heavily in at least a strong second place showing, but after 150 campaign events in the state he ended third after Paul.

Both he and Rick Perry dropped out of the race shortly before voting day in South Carolina and the two delegates allocated to Huntsman became unbound.

[37] The Gingrich victory in South Carolina, together with two strong debate performances, gave him a second surge, opening the race to a longer and more unpredictable campaign.

After the election Michigan GOP officials announced there had been an error in the memo published and that the two delegates would be given to the winner, sparking accusations of Romney rigging the results from Santorum's team.

According to Santorum and Paul supporters the slate was not as required based on the straw poll, but gave Romney a large majority of the delegates.

The state became the big battleground of Super Tuesday and its delegates were split between Romney and Santorum, who won three congressional districts where he did not have a full slate.

But Santorum suspended his campaign before the meeting in the Ohio GOP central committee deciding on the delegates took place and Romney dropped the dispute on May 4 in the interest of party unity.

He can show a plurality in six states and that secures him the opportunity of a place on the first ballot nominating the Republican candidate for president at the National Convention.

"[73] "We both agree that President Obama must be defeated," Santorum, 53, said in an e-mailed statement last night, "[Romney] clearly understands that having pro-family initiatives are not only the morally and economically right thing to do, but that the family is the basic building block of our society.

[80] Despite this, the following week 123 mostly Paul-aligned delegates, currently legally bound to support Romney at the convention, brought an ongoing federal lawsuit against the RNC and its chairman to instead be able to vote "in accordance with the free exercise of their conscience.

"[83] Also in June, the three remaining states voting in primaries, Utah, Nebraska, and Montana, added the final 101 delegates to attend the Republican National Convention.

[89][90] Ron Paul led a rally in Tampa Bay, Florida, on Sunday, the day before the Republican National Convention was to begin.

[91] Leading into the national convention, preliminary delegate counts {soft, firm} were: Romney{1,545, 1,399}; Paul{173,100}; Santorum{248,251}; Gingrich{142,143}; Others{1,3}; Available{147,63}; and Uncommitted{30,327}.

(e) If no candidate shall have received such majority, the chairman of the convention shall direct the roll of the states be called again and shall repeat the calling of the roll until a candidate shall have received a majority of the votes entitled to be cast in the convention.The primary election table below shows how and when the National Convention delegates are allocated and elected.

Notes Some of the state delegations made and announced their final decisions on Tuesday, the first full day of the Republican National Convention.