Republican stalwarts Newt Gingrich and New Jersey Gov. Chris Christie are at the top of Donald Trump's short list to be his vice presidential running mate, sources said, but the real estate developer is casting a wide net.

With less than three weeks to go until he is formally nominated at the Republican National Convention as the party's candidate in the Nov. 8 election, Trump's search for a No. 2 has intensified. The wealthy businessman, a political neophyte, has said he wants a political veteran to help him navigate the power corridors of Washington.

Gingrich and Christie, both loyal to Trump at a time when many Republican colleagues want nothing to do with him, would meet the New Yorker's requirement for experience — but would come with pluses and minuses.