Sen. Elizabeth Warren, D-Mass., at a November hearing of the Senate Banking, Housing and Urban Affairs Committee. A recent op-ed critical of Warren's brand of economic populism sparked an intraparty dispute among Democrats.
Sen. Scott Brown, R-Mass., attends the Republican National Convention in Tampa, Fla., on Aug. 30. Scott lost his re-election bid, but could be running for office again in a matter of weeks.
Chip Somodevilla/Getty Images
Republican U.S. Sen. Scott Brown (left) answers a question during a debate against Democratic challenger Elizabeth Warren on Monday at the University of Massachusetts in Lowell, Mass.
Bill Connell of Weymouth, Mass., who supports Republican Sen. Scott Brown, stands near signs supporting Brown's Democratic challenger, Elizabeth Warren, before the candidates' first debate Thursday in Boston.
Former President Bill Clinton hugs President Obama onstage after Clinton's rousing speech during the Democratic National Convention on Wednesday in Charlotte, N.C.
Justin Sullivan/Getty Images