UPDATE 2-New US Congress convenes, focused on recession

(Updates Pelosi re-elected House speaker, more details)

By Thomas Ferraro and Richard Cowan

WASHINGTON, Jan 6 (Reuters) - Democrats celebrated their increased clout in the U.S. Congress on Tuesday, swearing in new members who are expected to help President-elect Barack Obama enact a massive economic stimulus package.

Gavels sounded at about noon EST (1700 GMT), opening the Senate and House of Representatives a day after Obama visited the Capitol to press Republicans as well as fellow Democrats for quick action on a $775 billion package of tax cuts and new spending to stem a deepening recession.

Obama takes office on Jan. 20, which would give Democrats control of the White House and Congress for the first time in 14 years.

"We need action, and we need action now," Nancy Pelosi, a California Democrat, declared after colleagues elected her to a second term as House speaker.

Despite such challenges as the ailing economy, two wars and an estimated 46 million Americans without health insurance, the opening day of Congress amounted to somewhat of a victory party for the Democrats who expanded their control of the Senate and House in the November election.

"We are grateful to begin anew with a far more robust Democratic majority," said Senate Majority Leader Harry Reid.

Reid hailed Democrats' expanded majority, but echoed Obama's call for "change in Washington" after years of partisan bickering and gridlock.

"I say to my Republican colleagues: With American troops fighting two wars overseas, we are in this together," Reid said. "With the American people suffering a staggering economic crisis here at home, we are in this together."

The Democratic celebration in the opening of Congress was muted somewhat by a flap over a pair of seats that remained empty in the 100-member Senate.

TWO EMPTY SEATS

As lawmakers and family members partied, Democrat Roland Burris of Illinois, selected to fill the Senate seat vacated by Obama, was denied entrance.

The Illinois secretary of state refused to certify his appointment by scandal-plagued Illinois Gov. Rod Blagojevich, who had earlier been arrested and accused of attempting to sell the seat which had formerly been occupied by Obama.

Senate Democrats opposed the governor's action as tainted. The matter of certification is now in court in Illinois.

On a related front, Reid yielded to Republican pressure and put off an effort to seat comic-turned-politician Al Franken of Minnesota, also a Democrat. He faces legal challenges of his razor-thin election victory.