Fiorina, who herself lost a stepdaughter to drug addiction, broke into song on stage, rhapsodizing about how much she loves Cruz's young girls

The announcement is a last chance for Cruz to get momentum after an electoral drubbing by Trump in Tuesday's five Northeastern primaries

Ted Cruz made a sudden attempt to keep his presidential hopes alive by making Carly Fiorina his running mate – and she broke into song as she accepted the vice-presidential slot in what's likely to be a campaign in its final gasps.

'We've been traveling around the country and I've come to know Ted and Heidi and Caroline and Catherine!' said Fiorina, before lapsing into a sing-song voice about the two young Cruz girls.

'I know two girls that I just adore! I'm so happy I can see them more!' the former tech CEO trilled.

'Cause we travel on the bus all day. We get to play. We get to play!'

As a crowd in Indiana waited for another line of the made-up tune, Fiorina seemed to suddenly return to her senses.

'I won't bore you with any more of the song,' she said.

Cruz picked Carly a day after a humiliation in the five Northeastern primaries, which were all won convincingly by Donald Trump. The Texas senator placed third in all but one of them.

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It's Carly! Fiorina reprised her failed presidential campaign Wednesday alongside Texas Sen. Ted Cruz, who chose her as his running mate despite not being the favorite to win the GOP nomination

She sings, too: Former tech CEO Carly Fiorina broke into sing-song admiration of Ted Cruz's young daughters on Wednesday in Indiana as she accepted his offer of a running-mate slot

He praised his new political partner for standing up to the 'bully' billionaire in the fall when Trump was caught mocking Fiorina by saying Americans would never vote for 'that face.'

'In one of the earliest debates, Carly confronted Donald Trump, a man who in his characteristic understatement said of her: “Look at that face,”' Cruz told a crowd of supporters.

'And every one of us remember the grace, the class, the elan with which Carly responded – responded to Donald that she knew exactly what he was saying and that every woman in America knew exactly what Donald Trump was saying.'

Cruz recounted the episode, which played out in a September GOP debate after Trump got caught in a Rolling Stone interview mocking Fiorina's looks while watching her on a TV screen aboard his Boeing 757 jet.

Cruz used his much-hyped speech as a way to tee off on Trump.

He said Fiorina had 'faced challenges far worse than someone bellowing and yelling and insulting her face.'

He mentioned her loss of a step-daughter, but said: 'It is when you are facing the void when you are facing the abyss that you find your character.'

In a statement, the Cruz campaign called her 'a proven, consistent, courageous fighter. A fighter who terrifies Hillary. And who will do the same to our enemies.'

Cruz promised a 'major announcement' at his afternoon rally in Indianapolis, as the candidate tries to set Indiana as the next major battleground and Trump takes a victory lap after his Tuesday night electoral romp.

Surrogate daughters? Fiorina, who lost a stepdaughter to drug addiction, has latched on to Cruz children Catherine (left) and Caroline (right) since she endorsed the senator and has been campaigning with him

Not impressed: Donald Trump said Cruz's pre-emptive choice of a running made was 'a pure waste of time' since the senator is running a distant second to him

Cruz acknowledged it was 'unusual to make the announcement as early as we are doing so now,' even as he started describing his 'ticket' without having actually won the GOP nomination.

But he said the times demanded he act now, and that this was no ordinary election year.

Then, in a bizarre scene normally associated with a summer political convention, Cruz appeared on stage with a waving Fiorina in a bright red outfit.

'Today I am very proud and humbly honored ...I have accepted Ted Cruz’s offer to be his vice president to the Republican nomination,' Fiorina told the Cruz crowd.

Trump wasted no time mocking the exercise as 'a pure waste of time.'

'After massive defeats in Arizona, New York, Pennsylvania, Rhode Island, Delaware, Connecticut and Maryland, (in addition to twenty other contests) and given the fact that Senator Cruz has millions of votes less than me and is being clobbered on the delegate front,' he said in a statement, this is a pure waste of time.'

'Cruz has no path to victory – he is only trying to stay relevant,' Trump jabbed.

The Democratic National Committee fired a broadside at Cruz as soon as the news broke that he had chosen Fiorina, calling the selection of a woman the last gasp of a 'desperate and dying campaign.'

'It's fitting that a man best known for shutting down the U.S. government would select a woman best known for almost shutting down a great U.S. company,' DNC chief executive Amy Dacey said in a statement.

'In a dangerous and complex world, the only foreign policy experience Carly Fiorina can speak of is outsourcing American jobs to other countries and selling computer equipment to Iran in violation of international sanctions,' Dacey added.

The Democratic Party has clobbered Fiorina before: Last September it castigated her for attacking the abortion provider Planned Parenthood during a high-profile debate moment.

Peas in a pod: Cruz praised Fiorina's 'grace' in responding to attacks last fall from Donald Trump, their mutual mortal enemy

Trump, too, took a pre-emptive swipe at Fiorina – using her own past criticism of Cruz against them both.

In a video of a January CNN interview that Trump shared on Twitter, Fiorina is seen complaining that 'Ted Cruz is just like any other politician. He says whatever he needs to say to get elected.'

'Agreed!' Trump wrote in a one-word jab that accompanied the footage on Twitter.

He recycled the material from a tweet he fired off when Fiorina first endorsed Cruz in March.

Earlier on Wednesday, the presumptive GOP nominee said on the Fox News Channel that it would be surprising to see Cruz name a rnuning mate when he was trailing in the convention delegate count.

'I can't imagine he does it,' Trump sniffed.

'He's millions of votes behind, he's hundreds of delegates behind. ... He's got no path to victory, and he's naming a vice presidential candidate. I guess that's cute.'

'Naming Carly's dumb,' he declared, 'because Carly didn't do well. She had one good debate — not against me by the way, because I had an unblemished record of victories during debates — but she had one victory on the smaller stage and that was it.'

'She's a nice woman,' Trump added. 'I think that it's not going to help him at all.'

Cruz was back on the campaign trail Wednesday morning, surrounded by a throng of camera-toting reporters at an Indianapolis pancake house who asked how he would overcome Trump after the New York mogul ran up huge margins and won every county in five states that voted Tuesday.

'We have an event this afternoon, 4 pm .... we'll be making a major announcement at 4 pm so I encourage folks to come join us at 4 pm,' was all Cruz would say at the time.

Got his back: Fiorina was on stage with Cruz in Hershey, PA, earlier this month

She's with him: Fiorina was campaigning with Ted Cruz. He will formally announce she is his running mate at an Indianapolis rally

When reporters pressed him on the subject, Cruz answered: 'The entire purpose of this is that you guys can come, and at 4 pm you can find out the major announcement.'

Cruz wouldn't say if he would reveal his preferred vice presidential pick, despite earlier reports he might name Fiorina – on a day Trump was battling with Hillary Clinton over playing the 'woman card.'

'I have said from the beginning the most important thing for any running mate is that he or she should be prepared to step in and fulfill the role as president - be commander in chief, keep this country safe, and champion jobs, freedom, and security,' Cruz said.

The Hail Mary pass is noteworthy because normally it is the presumptive party nominee who names a vice president, usually in the days leading up to the convention.

In this case, Donald Trump is piling up a delegate lead – though Cruz hopes to snatch the nomination away from him at the convention if Trump fails to win the requisite 1,237 delegates' support.

Front-running Trump – who hasn't revealed his own vice presidential pick – has now top 50 per cent of the vote for five states in a row.

Fiorina performed well in multi-candidate debates where she stood out for scathing attacks on Clinton.

But her campaign petered out after New Hampshire, where she came in seventh, earning 4 per cent of the vote, or precisely 11,706 votes. She also finished seventh in Iowa.

She previously lost an effort to unseat California Sen. Barbara Boxer in 2010. She took hits on the campaign trail for job losses while she was at the helm of HP, and for lagging performance that ultimately led to her ouster – though Fiorina maintained reforms she put in place ultimately helped the company.

In the primaries, she regularly said that Hillary Clinton most feared tangling her on the debate stage, and said GOP voters would love to see her do the same.

Face-off: Fiorina earned props from pundits for her slashing attacks on Hillary Clinton in debates, and got the better of Donald Trump when he made an unkind comment about her personal appearance

She dominated the first undercard debate on Fox, and won a huge response in the second debate on the main stage by taking on Trump.

Trump had been quoted in a Rolling Stone piece referring to Fiorina by saying, 'Look at that face. Would anyone vote for that? Can you imagine that, the face of our next president?'

Fiorina responded: 'I think women all over this country heard very clearly what Mr. Trump said."

Fiorina's favorability numbers in a Morning Consult poll of registered voters just before she dropped were 26 percent favorable to 43 percent unfavorable.

She and Cruz both have family tragedies connected to drugs. Her stepdaughter died a drug addict, as did his sister.

While Cruz was plugging his afternoon rally, there was even speculation he might garner an endorsement from Indiana Governor Mike Pence, who is facing political problems at home for some of his conservative views on social issues.

Cruz mentioned Pence's name unprompted while discussing Indiana politics.

'There's been two incredible governors, Mitch Daniel[s], Mike Pence, that have reduced taxes, that have reduced regulations, and that has helped the job situation here in Indiana. But Indiana struggles with the 800-pound weight of the federal government still holding down job growth' Cruz said.

Last chance saloon: Ted Cruz, who was with his wife Heidi today, needs to do something to stop Trump's march.

Cruz is under pressure to demonstrate his path to victory after Trump's growing accumulation of delegates.

'I recognize that the New York media executives and the Washington lobbyists running Donald Trump's campaign both want the campaign to be over. They desperately want it to be over, because they recognize that this campaign has now moved onto much more favorable territory,' he said.

He minimized Trump's wins in New England and the Mid Atlantic as a 'home game.'

He called on Trump to 's how the humility to subject yourself to the scrutiny of Hoosiers' and take questions from Indiana voters.

Trump flew to Indiana Wednesday following a foreign policy speech in DC. He will hold a rally with hot-headed legendary Indiana University basketball coach Bobby Knight.

'Donald Trump doesn't like to do that. Donald Trump likes to parachute in like Mick Jagger, show up at a football stadium, give some performance, and then leave,' Cruz said.

'Well, this country isn't a reality show. And if Donald trump thinks he's too good to answer questions from the men and women of Indiana, that conveys something.'