Ted Cruz, Carly Fiorina

Carly Fiorina gestures to Republican presidential candidate, Sen. Ted Cruz, R-Texas, while taping an interview with Sean Hannity during a campaign stop in Orlando, Fla., Friday, March 11, 2016.

(Mike Carlson/The Associated Press)

Presidential candidate Ted Cruz is vetting a former rival - ex-Hewlett-Packard CEO Carly Fiorina - to be his pick for vice president despite trailing GOP frontrunner Donald Trump in the delegate count for the Republican nomination and having virtually no chance at beating the real estate mogul before the GOP convention this summer, a Fiorina aide told ABC News on Monday.

The aide, Sarah Isgur Flores, said the interest by the Cruz campaign did not include an offer to be the Texas senator's vice presidential nominee.

Fiorina, who earlier endorsed Cruz for president, suspended her campaign after a weak showing in the New Hampshire primary. The former tech executive was the Republican challenger to U.S. Sen. Barbara Boxer, R-Calif., in 2010.

Cruz campaign manager Jeff Roe tweeted Monday that the campaign has made a short list of running mates.

We have narrowed our VP candidates to a short list and are going thru the normal processes associated with picking a running mate.#CruzCrew — Jeff Roe (@jeffroe) April 25, 2016

Cruz and Ohio Gov. John Kasich are virtually assured of not receiving the 1,237 delegates necessary to capture the Republican nomination. Trump, the front-runner, leads the field with 845 delegates to 559 for Cruz and 148 for Kasich. But there is a strong possibility that this summer's Republican National Convention in Cleveland will be contested, with no candidate amassing enough votes on the first ballot.

The Texas senator and Ohio governor are concentrating their resources in remaining states favorable to themselves while backing out of contests where the other is more viable against Trump.

Trump called the so-called alliance between Cruz and Kasich "pathetic," according to CNN.