Rick Santorum suspended his 2012 presidential campaign on April 10, 2012, after winning 11 Republican Party primaries and caucuses. The move allowed presumed nominee Mitt Romney a clear path to the nomination at the party’s summer convention.

See also:2012 Republican Primary Results

Here are five reasons Santorum quit the race despite winning more than a million Republican votes:

1. Santorum Was Losing His Home State

Two statewide polls conducted in April 2012 showed Santorum losing his home state of Pennsylvania.

Three weeks before the state’s April 24 primary, Public Policy Polling found Romney leading Santorum by 5 percentage points. And two weeks before the primary, the day after Santorum abandoned his campaign, American Research Group Inc. found Romney up by 4 percentage points.

Political analysts agreed that Santorum needed not only to win his home state, but win it by a wide margin to erase concerns about his viability as a candidate. Losing Pennsylvania, they said, would have been humiliating and damaging to his future aspirations, perhaps for president in 2016.

Santorum had been rejected by Pennsylvania voters in a statewide election once before, in 2006, when he was seeking re-election to the U.S. Senate. Romney seized on Santorum’s Senate loss in a television ad that stated: "We fired him as senator. Why promote him to president?"

2. Santorum Ran Out of Money

Santorum told supporters after dropping out of the 2012 presidential race that his campaign was being outspent badly by Romney, and was in debt about $1 million.

“We have been outspent in most states 5-1 or even 10-1. And we still won, or we've come incredibly close,” Santorum said. “Iowa and the three-state sweep. An over 20-point win in Louisiana. Only a few votes short of victory in Michigan and Ohio. We have made history. There has been no other Presidential comeback race like ours.”

3. Texas Primary Rules

Santorum was pressing the Republican Party in Texas to change the way it allocates its 155 delegates to winner-take-all, a move that would have allowed his to close the gap between himself and Romney quickly. But the party declined, and said it would continue awarding it delegates on a proportional basis.

“Our good friends in Texas have been working non-stop to make sure that they have a say in the choice of our nominee, but without the state changing its delegate allocation to winner-take-all, I do not see a path forward that does not risk our shared objective of defeating Barack Obama in November,” Santorum said.

4. Santorum Daughter Illness

Santorum’s daughter Isabella Maria, or "Bella," had been hospitalized for pneumonia over several days in early April 2012, forcing the candidate to briefly suspend his campaign. Santorum said he used the break to talk with his family about whether to stay in the race or quit.

Bella was born in 2008 with a rare genetic disorder called Trisomy 18. Most children born with the condition do not live beyond the first year of their lives.

"This was a time for prayer and thought over this past weekend," Santorum said. "Just like it was when we decided to get into this race ... we were very concerned about our role of being the best parents we possibly could to our kids.”

Santorum described it as “one of the hardest decisions Karen and I have ever had to face together.”

5. Newt Gingrich

The former speaker of the House of Representatives refused to drop out of the race despite winning only his home state of Georgia. Santorum and Gingrich competed for support from the same evangelical, Tea Party conservative voters. "I am committed to staying in this race all the way to Tampa so that the conservative movement has a real choice," Gingrich said.

Santorum could not make significant headway toward the goal of 1,144 delegates needed for the nomination with Gingrich in the race.