Texas Sen. Ted Cruz announced Hewlett-Packard executive Carly Fiorina as his running mate Wednesday afternoon, part of a last-ditch effort to prevent front-runner Donald Trump from clinching the GOP nomination outright.

Cruz called Fiorina an "extraordinary leader" who is "brilliant and capable."

"She is careful, she is measured, she is serious," Cruz said at an Indianapolis rally in which he emphasized her business credentials.

Cruz painted Trump and Democrat Hillary Clinton as "two big-government liberals" and said a presidential ticket with himself and Fiorina would help unite the party and country against special interests that he said would thrive under an administration led by either.

The announcement came a day after the path for a Cruz win at the GOP convention narrowed significantly. Trump's primary victories in a handful of mid-Atlantic states Tuesday put him within 300 points of winning on the first ballot in Cleveland.

The vice presidential announcement came earlier than is typical in the presidential race. Here's more from the Associated Press:

Some Cruz allies praised the selection of Fiorina, but privately questioned if it would change the trajectory of the race. Trump has won 77 percent of the delegates he needs to claim the nomination, and a win next week in Indiana will keep him on a firm path to do so.

Cruz fired back at critics during his introduction of Fiorina, saying that no candidate would score the 1,237 delegates necessary to win on the first ballot in Cleveland.

“The mainstream media, the New York media executives and the Washington lobbyists are all trying to tell the American people this race is over. But where we are right now nobody is getting to 1,237 delegates. I’m not getting to 1237 and Donald J. Trump is not getting to 1237 delegations,” Cruz said. “The Hoosier State is going to have a powerful voice in making that clear.”

The Cruz campaign is focusing heavily on winning Indiana, where voters hit the polls Tuesday. Fifty-seven delegates are at stake in that contest and Cruz officials have made a pact with the John Kasich campaign to back off Oregon and New Mexico in exchange for the Ohio governor standing down in the Hoosier State.

Cruz is banking that his VP selection could particularly aid his campaign in California, Fiorina's adopted home state in which she unsuccessfully ran for Senate in 2010. Voters hit the polls there on June 7 and 172 delegates are at stake.

Fiorina framed the election cycle as a fight for the soul of the GOP and the country.

"I’ve had tough fights all my life. Tough fights don’t worry me a bit," she said. "What matters is that it’s the right fight ... This is a fight for all of us: for our party, for our future, for our children’s’ future.”

Fiorina sought the GOP presidential nod earlier this cycle but dropped out in February. She generated some momentum after a strong performance at an early debate but ultimately failed to build a strong following in the lead-up to the Iowa and New Hampshire contests.

She did receive 1,146 votes in Georgia's primary, according to the secretary of state's office.

She endorsed Cruz last month ahead of the Florida nominating contest.

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