4 Issues That Hurt Ted Cruz Ahead of the Suspension of His Campaign

— -- There were warning signs that things were going south for Ted Cruz ahead of his loss in Indiana tonight and the subsequent suspension of his presidential campaign.

A combination of momentum working against him and some last-ditch efforts that were perceived by some as desperate landed Cruz squarely in second place in the Indiana Republican primary.

"We gave it everything we've got, but the voters chose another path and so with a heavy heart, but with boundless optimism, for the long term future of our nation, we are suspending our campaign," Cruz said tonight, adding that he is not "suspending our fight for liberty."

Here are four issues that appear to have led to the end for Cruz:

Momentum Mess

Going into Indiana, it appears that Donald Trump had accrued enough momentum to help him win the state.

The Indiana primary came a week after the so-called "Acela" primary of five northeastern states, which Trump swept, and two weeks after Trump's dramatic victory in his home state of New York.

James Campbell, a professor of political science at the University at Buffalo, said that there was "something of a momentum shift" in the Republican race after those primaries that impacted the results in Indiana.

"That kind of got people thinking that Trump was inevitable and that usually brings some undecideds or torn voters to a candidacy," Campbell told ABC News.

A Less-Than-Stellar Endorsement

Cruz hoped to replicate his Wisconsin victory in Indiana as both are Midwestern states with similar demographics. And in both Indiana and Wisconsin, Cruz had the endorsements of their respective Republican governors.

That said, Indiana Gov. Mike Pence's endorsement was not quite as enthusiastic as Wisconsin Gov. Scott Walker's.

While Walker regularly campaigned alongside Cruz, Pence made his endorsement during a radio show appearance and went on to give Trump a shout-out during his endorsement of Cruz, saying, "I like and respect all three" of the Republican candidates.

A Failed Alliance

Ohio Gov. John Kasich and Cruz paired up, in theory, agreeing to coordinate their campaigns in order to raise their party's chances of beating Trump.

But, according to a NBC/WSJ/Marist poll in Indiana released on Sunday, there were more voters in the state that disapproved of the short-lived "alliance" than those that did.

Fifty-eight percent of likely Republican primary voters in Indiana said they disapproved of Cruz and Kasich teaming up to beat Trump in the Hoosier State, while 34 percent said they approved of the move.

'Desperate' Move

Cruz added his name to the history list, becoming the second Republican candidate ever to name a vice presidential nominee before becoming the nominee himself.

It didn't help Ronald Reagan back in 1976 when he was the first person to do it, and it didn't help Cruz the second time around.

According to a CNN/ORC national poll released Monday, 67 percent of Republicans said that Fiorina's addition did not have much effect on how they would vote, while 18 percent said it made them more likely to vote for Cruz and 14 percent said less likely.

Marjorie Hershey, a political science professor at Indiana University, said that the Fiorina announcement showed "increased desperation on the Cruz campaign."

"It's not normally regarded as the action of a likely winner. ... Why would he need to do that if he felt really confident?" she told ABC News.

Campbell said that both the alliance and the Fiorina announcement were likely an effort to not only stop the bleeding but also turn the race around.

"I think those moves were meant to short circuit or reset the campaign that seemed to be drifting away from them," Campbell said. "I don't think they caused the drift, I think the drift was caused by momentum and other things."