WASHINGTON (AP) — When the next Congress cranks up in January, there will be more women, many new faces and fewer tea party-backed House Republicans from the class of 2010.

Overriding those changes, though, is a thinning of centrist veterans in both parties. Among those leaving are some of the Senate’s most pragmatic lawmakers, nearly half the House’s centrist Blue Dog Democrats and several moderate House Republicans.

That could leave the parties more polarized even as President Barack Obama and congressional leaders talk up the cooperation needed to tackle complex, vexing problems such as curbing deficits, revamping tax laws and culling savings from Medicare and other costly, popular programs.

"This movement away from the center, at a time when issues have to be resolved from the middle, makes it much more difficult to find solutions to major problems," said William Hoagland, senior vice president of the Bipartisan Policy Center, a private group advocating compromise.

In the Senate, moderate Scott Brown, R-Mass., lost to Democrat Elizabeth Warren, who will be one of the most liberal members. Another GOP moderate, Richard Lugar of Indiana, fell in the primary election. Two others, Kay Bailey Hutchison of Texas and Olympia Snowe of Maine, are retiring.

Moderate Democratic senators such as Kent Conrad of North Dakota, Herb Kohl of Wisconsin, Ben Nelson of Nebraska, James Webb of Virginia are leaving, as is Democratic-leaning independent Joe Lieberman.

While about half the incoming 12 Senate freshmen of both parties are moderates, new arrivals include tea party Republican Ted Cruz of Texas, conservative Deb Fischer of Nebraska, and liberals such as Tammy Baldwin of Wisconsin and Hawaii’s Mazie Hirono.

There’s a similar pattern in the House.

"Congress seems to be going in the opposite direction of the country, just as the country is screaming for solutions to gridlock," said Democratic strategist Phil Singer.