Sen. Ted Cruz's sudden exit from the GOP presidential race Tuesday night in Indiana caught his supporters off guard. Many of them clearly understood that he was putting everything his campaign had left into winning the state.

Earlier Tuesday, as voters were going to the polls, his campaign advertised rallies on Wednesday in Nebraska and Washington, two states with upcoming primaries where Cruz was thought to have a chance to win.

RELATED: Cruz exits race after Trump's Indiana win

What changed was the magnitude of Trump's victory in Indiana, a conservative Midwestern state that was supposed to be "favorable" ground for Cruz, as had been Wisconsin, Cruz's last primary victory.

But the bounce from Wisconsin was short-lived, followed by resounding defeats in New York - Trump's home state - and five other northeastern states.

Had he chosen to fight on, the delegate count could have given him at least reason for doing so, arguing that Trump, even with his delegate haul from Indiana, still had not clinched the 1,237-delegate majority to lock down the GOP nomination.

RELATED: Ted Cruz: 'We are headed to a contested convention'

There was, however, more to consider than the delegate tally. Instead of watching the polls narrow after Wisconsin, Cruz was seeing polls widen in Trump's favor across the country, particularly in California, the last and largest delegate bonanza in the GOP race, on June 7.

Even at home the news was looking worse for Cruz.

Among Texas Republicans, who Cruz won over by a comfortable margin on March 1, a new poll commissioned by the Texas Bipartisan Justice Committee showed Trump leading with 45 percent compared to 40 percent for Cruz.

That Trump momentum would have made it increasingly hard for Cruz to enter the national convention short-handed with the hope of turning Trump delegates in his favor - the only strategy he had left since New York, when it became mathematically impossible to reach the magic number of delegates before the convention.

RELATED: After N.Y. loss, Cruz officially aims at long slog to contested convention

From the beginning, strategists credited Cruz with a shrewd understanding of the 2016 GOP landscape. While party heavyweights like Jeb Bush seemed to corner the insider market, Cruz understood that the party base was looking for an outsider.

Cruz would occupy that outside "lane" and force a showdown with an insider establishment candidate like Bush.

What he didn't see over his shoulder was Trump coming up behind him, taking over that outsider lane. Cruz tried a brief alliance of convenience, hoping Trump would fade on his own. But eventually he had to engage in the "cage match" with Trump he had hoped to avoid.

He lost.

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"Cruz knows that you've got to be able to have money and momentum," said Matt Mackowiak, an Austin-based GOP consultant. "He knew it wasn't going to happen. He knew it was going to get worse after tonight."

Indiana had widely been described as a "last stand" for the Cruz campaign. A victory there only would have stopped Trump from certain domination. It would not have opened up an easy path to the nomination.

Still, Cruz is likely to remain a major conservative player in the GOP, despite his unpopularity in Congress and within the party establishment. He commands an active faithful following, and he's worked intently toward his presidential ambitions for almost 30 years. He'll be back, but not as an outsider. Soon he'll turn to his 2018 Senate campaign, and then 2020 is not far off.

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Cruz kicked off the presidential election last March on a novel platform of challenging his own party's so-called establishment. It seemed like a long shot, but Cruz was ahead of his time, and he brazenly defied media expectations to become the long-standing runner-up in the GOP primary.

"He was really well-positioned to be the outsider candidate this cycle, then Trump came in and screwed that up," Mackowiak said.

Most experts blame his failure on a very narrow appeal to evangelical Christians and conservative stalwarts. He positioned himself on the extreme right and was detested by many of his Senate colleagues.

But Cruz was a brilliant lawyer and assembled an outstanding campaign with high technology and innovative social media tactics.

"That's going to be a prototype for students of campaigns to look at for a long time," said Jerry Pollinard, a veteran political scientist at the University of Texas Panamerican.

RELATED: Cruz's spending tactics take modern twist

The operation caught Trump off guard in Iowa, the nation's first caucus, where Cruz came in first. He'd mobilized an unprecedented grassroots effort there, with dormitories for volunteers from across the country.

Observers wondered if Cruz's command of the evangelical vote could carry him through the election. But when a round of typically evangelical Deep South states voted on Super Tuesday and mostly leaned toward Trump, Cruz's grip on that electorate slipped.

RELATED: Trump surprises with evangelical endorsement

Though Cruz's narrow appeal may have hindered his campaign, he outlasted and outpolled the supposedly broad-based moderate candidates, Bush, Florida Sen. Marco Rubio and New Jersey Gov. Chris Christie, among them. On Tuesday, Cruz fell to the same force as his rivals before him: Trump.

"I think it was hard for any of the candidates to overcome the extraordinary amount of free media that Trump has gotten from the press," said Erick Erickson, a prominent conservative and a leader in the #NeverTrump effort.

Cruz described himself as the one true conservative in the race. But in the end he couldn't compete with Trump's popularity with working-class whites, especially men, and his frequent outrageousness.