Chris Christie’s presidential ambitions are in a lot of trouble. First he squandered his initial strength in national polls — he holds 6 to 7 percent of the vote among Republican contenders, down from about 20 percent before the scandal involving the closing of lanes to the George Washington Bridge.

Now a fairly broad set of reporting indicates that Mr. Christie, the governor of New Jersey, is struggling to build support among the donors, officials and operatives necessary to win the nomination.

He probably couldn’t have won the nomination in any case — because of his moderate positions on immigration, gun control and Medicaid expansion — but he seemed poised to earn substantial support from many self-described moderate voters, along with many donors in the Republican establishment. The severity of his challenge is therefore quite important, because it puts Jeb Bush in position to consolidate the moderate wing of the G.O.P.