Eyes on Rubio as Republicans take debate stage in Milwaukee

Republican presidential candidates take the stage in Milwaukee on Tuesday night for a debate focused on the economy, with voters and donors looking to see if U.S. Senator Marco Rubio can produce a strong performance and grab the mantle of party establishment favorite.

SEE MORE:Your guide to tonight's debate

Eight Republicans seeking the party's nomination for president in the November 2016 election will face off on Fox Business Network at 9 p.m. EST (0200 GMT Wednesday). It is a smaller field than three past debates after two candidates were bumped to the earlier, "undercard" forum.

Voters will watch how the candidates, including retired neurosurgeon Ben Carson and real estate magnate Donald Trump, handle detailed policy questions after criticism that their policy proposals are too vague.

See images of the last CNBC debate:

Rubio is under pressure to show he can fight off recent criticism of his experience and his stance on abortion, as he tries to unseat fellow Floridian Jeb Bush as the favorite of the party's mainstream. Rubio has not led polls in any early voting state, and lags Bush and others in fund-raising. A strong performance like one he had at the last debate two weeks ago could change that.

"Right now, the establishment money guys are wondering, if not Bush, then who?" said Saul Anuzis, a former chair of the Michigan Republican Party who is backing U.S. Senator Ted Cruz of Texas. "Rubio has to show the leadership establishment types that he would be a good alternative to Bush."

The last debate gave Rubio a high-profile boost and a flood of new donations.

Bush, who has struggled to explain his policy proposals in a down-to-earth way, needs a steady performance to calm his supporters. A TV ad by his Super PAC planned for key states emphasizes his experience. "It's not about yapping, it's not about talking, it's about doing," he says in the ad.

Tuesday's focus on the economy could help some candidates avoid addressing topics that dogged them in recent weeks.

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Rubio's campaign recently released credit card records to fend off rumors he misused party funds while in Florida's legislature. Front-runner Trump tweeted that Rubio was "a total lightweight who I wouldn't hire to run one of my smaller companies."

Carson has faced questions about details of his life story and his involvement with a dietary supplement company that ran into trouble with regulators. He told CNN he used the product but never meant to publicly endorse it.

For more on the 2016 U.S. presidential race and to learn about the undecided voters who determine elections, visit the Reuters website. (http://www.reuters.com/election2016/the-undecided/)

(Reporting by James Oliphant and Erin McPike in Washington, and Emily Stephenson and Steve Holland in Milwaukee; Editing by Alistair Bell)