Once considered a heavy favorite for the Republican nomination, Jeb Bush will try to energize his presidential campaign on Wednesday when he goes into a prime-time debate where Donald Trump looms large.

The former Florida governor, an establishment Republican, has been overshadowed by Trump's bomb-throwing rhetoric in the contest to become the party's candidate for the November 2016 election.

Bush has to show some fervor in the debate in California, said Austin Barbour, senior advisor to a Super PAC that supported former Republican candidate Rick Perry.