By Theodore Schleifer and Eric Bradner CNN

INDIANAPOLIS, Indiana (CNN) -- Ted Cruz, having been trounced by Donald Trump in six consecutive states, has gone from banking on an Indiana win to facing a campaign collapse without one.

The surreal elevation of Carly Fiorina to his presidential ticket on Wednesday was the latest sign of Cruz's increasingly narrow path to the Republican nomination, a campaign that is depending on a series of desperate attempts to widen it ever so slightly. Cruz's campaign is throwing a variety of messages against the wall here, hoping something will stick, and also reviving the labor-intensive ground games that helped it win Iowa and Wisconsin.

If the campaign can flip a race trending against it and live to fight to California, then maybe, the theory goes, it can draw the inside straight needed to keep Trump from securing the 1,237 votes needed to win the GOP nomination and then win a contested convention in Cleveland.

"It is unusual to make the announcement as early as we are doing so now," Cruz said Wednesday in introducing Fiorina. "Well, I think all would acknowledge this race -- if anything, it is unusual."

Cruz allies and people close to the campaign describe a budding sense of gloom, with internal polls diving as Trump mounted even stronger than expected showings in his native northeast. In Indiana, which Cruz backers once believed they were favored to win after his strong defeat of Trump in Wisconsin, Cruz's numbers have fallen precipitously: Once leading, Cruz now trails in the state by eight to 10 points, according to a person who has seen the numbers, with Trump over the 40% mark. Cruz's campaign did not respond when asked about those figures.

Cruz has wanted a one-on-one matchup against Trump for months, and a deal with John Kasich over the weekend has given him one here. The arrangement -- Kasich would leave Indiana and Cruz would vacate Oregon and New Mexico -- doesn't guarantee Cruz will pick up voters left behind or unhappy with Trump, however.

"Lyin' Ted Cruz, who can never beat Hillary Clinton and has NO path to victory, has chosen a V.P.candidate who failed badly in her own effort," Trump tweeted Thursday morning.

Before the Fiorina announcement, Cruz was in search of a message that could resonate in Indiana -- and a way to explain how he'd managed to lose five states to Trump in one night.

In Knightstown on Tuesday night, he told voters not to pay attention to pronouncements that the race is effectively over -- that such analysis is only designed to benefit "the media's chosen candidate," Trump. The billionaire, however, is the only candidate who can hit 1,237 delegates before the convention, and needs to win only 50% of the remaining delegates to do so, according to CNN estimates.

Cruz said news executives would be the most gleeful about Trump's round of wins -- not because they support Trump, but because they see him as the weakest candidate against Hillary Clinton.

"Donald had a good week. He had a good week in the northeast, where he lives and Donald's very worried because this race shifted to much more favorable terrain," Cruz told reporters in Fort Wayne on Thursday. "I think Indiana will be a pivotal state for the entire country. And so Donald, sadly aided and abetted by media network executives who are all liberal Democrats who are all rooting for Hillary, are quick to say the race is over. "

That media-bashing was also a way for Cruz to tee up another tactic against Trump: Cramming the words "Donald and Hillary" into nearly every sentence while laying out a list of 13 policy areas on which he said Trump and Clinton hold similar positions.

"Donald Trump and Hillary Clinton are virtually indistinguishable on policy issues across the field," Cruz said Thursday. "Donald Trump and Hillary Clinton both have come out in support of raising taxes and I think the people of Indiana pay too much in taxes already. As President, I'm going to cut your taxes, we're going to adopt a simple flat tax and abolish the IRS."

Fiorina and Cruz have already cut a 30-second TV ad, narrated by the new running mate and emphasizing the Trump-as-Clinton message. "Neither Hillary Clinton nor Donald Trump will fight the system, because they are the system," Fiorina says in the ad.

To appeal to voters in central Indiana, Cruz has also adopted a Trump talking point, highlighting Indianapolis air-conditioning manufacturer Carrier's decision to shift its jobs to Mexico. Trump has consistently cited the announcement -- which has gone viral on video -- as a sign of America's trade imbalance with Mexico.

Cruz's successes of late have come in winning the inside baseball delegate battle, organizing states like Colorado and Maine for people who would support the Texas senator on a second ballot and beyond. But Trump has managed to turn that against Cruz, saying that activity is a sign the system is "rigged" against political outsiders like himself.

"There's a lot of pessimism seeping in," said Erick Erickson, a commentator close to the Cruz campaign and a leading anti-Trump voice. "Psychologically, I think he does have to win Indiana."

The strategy: reprise Iowa and Wisconsin

The opening days of Cruz's campaign here, where he has been firmly planted since Saturday despite the northeastern contests, has featured the Texas senator reliving his Iowa days, with small town stops like those which led him to victory in the first-in-the-nation caucuses in February.

At Oasis Diner in Plainfield, Cruz hopped into the bed of a red pickup truck before heading inside to greet would-be voters. In Columbus, daughters Caroline and Catherine got a treat at an ice cream shop.

"With Iowa and Wisconsin, it was kind of a slow build of steady momentum, and then kind of a break at the end," said Bob Vander Plaats, president of The Family Leader and Cruz's national co-chair. "That blend and that mix bodes very well for him to be successful there."

Cruz will need to run up the score in heavily evangelical northeastern Indiana near Fort Wayne, while Trump is expected to sweep the south, particularly in Evansville, where he held a massive rally Thursday.

He is banking on an evangelical-infused volunteer base that powered the campaign to grassroots victories twice before. Outside of Indianapolis, the latest iteration of Camp Cruz is being pitched as a chance for volunteers to "sacrifice" themselves for a greater cause.

"Like Wisconsin, Indiana can turn the tide for us. It is a momentum changer," read one email to Cruz supporters Tuesday night. "We know this is a last minute request. But please get to Indianapolis. Ted Cruz needs you."

Not everything can be replicated, however.

Conservative radio hosts in Indiana range from Trump-friendly to Trump-tolerant, unlike the anti-Trump screeds that echoed over dials in Wisconsin. And the state GOP establishment has not consolidated around Cruz the way it has elsewhere.

The two leading Republican lights, Gov. Mike Pence, a social conservative warrior, and former Gov. Mitch Daniels, a former senior George W. Bush administration official, have shown no signs of being anything beyond neutral this week -- stripping Cruz of powerful validators that could swing a toss-up his way.

Cruz's Indiana team does feature influential behind-the-scenes operators. The campaign hasn't yet released the full roster, but on it will be Brandt Hershman, one of Indiana's three most influential state senators; Tim Rushenberg, a former agency head under Daniels who's now an energy lobbyist; and Curt Smith, a religious conservative lobbyist who has the ears of Pence and several of the state's members of Congress, according to Rushenberg and two other members of Cruz's Indiana team who were on hand at Wednesday's Fiorina event.

And at least three super PACs, including two explicitly backing Cruz, are spending more than $3.8 million -- already almost twice as much as those groups spent in Wisconsin.

David McIntosh, a former Indiana congressman and the head of one of those groups, the Club for Growth, said its polling showed a static, tight race. And he promised to spare few expenses to make it happen: "It's a necessary win, so we'll spend the resources it takes."

Fiorina's possible boost

The ironic part of Cruz's emphasis on a one-on-one matchup against Trump is that with Fiorina, he has created a two-on-one contest.

The most important voters in the state could be the more moderate Republicans who make up the Indianapolis suburbs. Voters in those areas -- whose political identities were largely shaped by Daniels -- would have made up Kasich's base.

Particularly important are suburban women, who Indiana Democrats have courted for years -- but could be more inclined to participate in the Republican contest, with Cruz tapping Fiorina as his vice presidential pick and a competitive Senate primary fueling interest in the GOP ballot.

Jeb Bush, in his first interview since dropping out of the presidential race, praised Cruz's Fiorina pick as a "smart move." Bush, who has endorsed Cruz, told CNN's Jamie Gangel in an interview that Fiorina would prove a useful foil to both Trump and Clinton.

"I'm impressed with her," the former Florida governor said. "Picking a candidate that is talented, tough -- she takes on Trump really well, I think, and she takes on Hillary Clinton very well, as well. (She's) someone who's got a proven record, who's been vetted by a candidate, I thought it was a smart move."

Her selection also seems as calibrated for a payoff in California as it does in Indiana. Cruz's fate is likely to be sealed either way in that state's primary on June 7, when his campaign and Kasich's are together hoping to deny Trump a massive haul in the state's 53 congressional districts.

Yet Reed Galen, a California Republican hand, predicted that Fiorina would nevertheless only have a modest impact in the state. A former statewide GOP star, Fiorina is expected to be a draw in one of the most important states left on the Republican calendar -- but she lacks a political network in the state she left over five years ago.

She and Cruz will head together this weekend to the California GOP convention.

"None of it matters, the Carly move, where they send her, et cetera, if they don't win Indiana next week," Galen said.

Only Indiana, he added, is "keeping the Cruz campaign's viability and credibility from crumbling."

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