PROVIDENCE, R.I.  In an election year when anger and mistrust have upended races across the country, toppling moderates and elevating white-hot partisans, Mayor Michael R. Bloomberg is trying to pull politics back to the middle, injecting himself into marquee contests and helping candidates fend off the Tea Party.

New York’s billionaire mayor, whose flurry of activity is stirring a new round of speculation about his presidential ambitions, is supporting Republicans, Democrats and independents who he says are not bound by rigid ideology and are capable of compromise, qualities he says he fears have become alarmingly rare in American politics.

Next month, Mr. Bloomberg will travel to California to campaign for Meg Whitman, the eBay entrepreneur and Republican running for governor on a platform of corporate-style accountability and fiscal prudence. He visited Rhode Island on Thursday to champion Lincoln D. Chafee, a Republican turned independent who is locked in a three-way battle for the governor’s office.

And, in perhaps the mayor’s most direct confrontation with a Tea Party candidacy, he will host a fund-raiser at his Manhattan town house for Harry Reid, the Senate majority leader facing an unexpectedly forceful challenge from Sharron E. Angle, a political neophyte backed by Sarah Palin.