* Democrats score wins in Massachusetts, Indiana, Wisconsin
* Both parties seen digging in fight over taxes, spending cuts
By David Lawder
WASHINGTON, Nov 6 (Reuters) - Democrats retained control of the U.S. Senate on Tuesday night, taking over hotly contested Republican seats in Massachusetts and Indiana while holding on to most of the states they already had, including Wisconsin and Virginia, according to projections.
The most significant turnover victory for Republicans came in Nebraska, where conservative candidate Deb Fischer, endorsed by former Republican vice presidential candidate Sarah Palin, was the projected winner in a race for the seat of retiring Democrat Ben Nelson.
Overall, the balance of power appeared poised to remain unchanged in Congress - likely meaning more partisan gridlock - as Republicans were projected to remain firmly in control of the House of Representatives. Television networks also projected that Democratic President Barack Obama won re-election.
While the Senate did not change hands, it could wind up as a more polarized body, with fewer moderates in the ranks of both parties.
That scenario was underscored by two victories in particular.
Elizabeth Warren, the winner over moderate Scott Brown in Massachusetts, is an activist Harvard Law School professor strenuously opposed by Wall Street interests.
In Texas, the seat of a retiring Republican, Kay Bailey Hutchison, was filled in an easy victory by Ted Cruz, a favorite of the conservative Tea Party movement.
As Congress pivots from elections to the year-end “fiscal cliff” of expiring tax cuts and the launch of automatic spending cuts, the results portend a continued bitter divide.
“That means the same dynamic, that means the same people who couldn’t figure out how to cut deals for the past three years,” said Ethan Siegel, an analyst who Washington politics for institutional investors.
House Speaker John Boehner said voters wanted to continue Republicans’ agenda, but pledged to work “with any willing partner.”
“With this vote, the American people also made clear there’s no mandate for raising tax rates,” Boehner told party activists in Washington.
With Obama’s projected re-election and the Democratic Party retaining a m ajority in the Senate, Democrats too are seen as emboldened to push their plan for tax fairness - cutting budget deficits by asking wealthy Americans to pay higher tax rates, while extending lower rates for the middle class.
But there is less than two months before tax cuts enacted under President George W. Bush expire on Dec. 31, thrusting higher tax rates on all Americans. Two days later, $109 billion in across-the-board spending cuts begin to bite. If unchecked by Congress, the fiscal cliff would suck some $600 billion out of the U.S. economy next year.
Obama’s Democrats also beat back Republican challengers in Ohio, Florida, Connecticut and Pennsylvania.
In Maine, independent Angus King won easily in the contest to replace retiring Republican Olympia Snowe and is widely expected to side with Democrats on many issues, handing them another seat.
In Indiana, a state with a large majority of Romney voters, Democrat Joe Donnelly pulled an upset victory against Republican and Tea Party favorite Richard Mourdock, whose prospects faded after he made inflammatory comments that pregnancy after rape could be “something that God intended.”
Mourdock had defeated longtime Indiana moderate Republican Richard Lugar in the Republican primary.
A well-financed Democratic campaign in Massachusetts for Warren proved successful, unseating Republican Scott Brown, who had succeeded the late liberal champion Edward Kennedy in a special election in 2010.