By David Lawder and Fred Barbash
WASHINGTON (Reuters) - The top Democrat in the Senate warned on Thursday that the United States looks to be headed over the "fiscal cliff" of tax hikes and spending cuts that will start next week if squabbling politicians do not reach a deal.
Majority Leader Harry Reid told the Senate in a speech that "it looks like that is where we're headed.
He called on the Republicans who control the House of Representatives to prevent the worst of the fiscal shock by getting behind a Senate bill to extend existing tax cuts for all except those households earning more than $250,000 a year.
With the House not in session and the clock ticking toward the scheduled January start of tax increases and deep, automatic government spending cuts, Reid offered little hope.
"I don't know time-wise how it can happen now," he said.
President Barack Obama arrived at Andrews Air Force Base outside Washington after a flight from Hawaii on Thursday on his way back to the White House to try to restart stalled negotiations with Congress.
Obama made phone calls to congressional leaders on Wednesday from his vacation in Hawaii to try to revive the stalled talks to prevent the "fiscal cliff" scenario, which would worry world financial markets and could push the United States back into recession.
U.S. stocks fell to session lows after Reid's pessimistic remarks.
In addition, consumer confidence fell to a four-month low in December as the budget crisis sapped what had been a growing sense of optimism about the economy, a report released on Thursday showed.
"People are hearing about (the cliff) and it negatively impacts confidence and investor sentiment and even holiday sales," said Todd Schoenberger, managing partner at Landcolt Capital in New York.
The chances of a last-minute deal - at least one that would prevent tax hikes - remained uncertain, with Republicans and Democrats each insisting the other side move first amid continuing partisan gridlock.
The Senate, controlled by Democrats, was scheduled to meet later on Thursday but on matters unrelated to the "fiscal cliff."
Speaker John Boehner and other House Republican leaders, who say they are willing to take up a "fiscal cliff" measure only after the Senate acts on one, were to hold a conference call with Republican House members on Thursday.
The expectation for the call was that lawmakers would be told to get back to Washington within 48 hours to consider anything the Senate might pass.
Weather permitting, that would bring them to Washington with perhaps three days left before the deadline for action. Storms affecting the Midwest, the South and the Northeast played havoc with airline schedules.
"This isn't a one party or one house problem. This is (that) leaders in both parties in all branches of the government are not willing to make the deal that they know they have to make. Everybody wants their stuff but doesn't want to give up what they don't want to give up," Republican U.S. Representative Steven LaTourette told CNN.
The House and Senate passed bills months ago reflecting their own sharply divergent positions on the expiring low tax rates, which went into effect during the administration of Republican former President George W. Bush.
Democrats want to allow the tax cuts to expire on the wealthiest Americans. Republicans want to extend the tax cuts for everyone.
Congress has proven that it can act swiftly once an agreement is reached. Hope persisted that Republicans and Democrats might come up with a resolution before New Year's Day that could at least postpone the impact of the tax hikes and spending cuts while further discussions take place.
That gives some hope to world markets.
"There is still hope for a last-minute deal, otherwise we're in for a correction in January. People have already priced in an agreement. Without it, the market can't stay at these levels," a Paris-based trader said.
Another battle is just over the horizon in late January or early February over raising the debt ceiling, which puts a limit on the amount of money the U.S. government can borrow to pay its debts and can be raised only with the approval of Congress.
Republican leaders have said they will insist on more budget cuts as a condition of raising the ceiling. Without any action, the U.S. Treasury said on Wednesday the government is set to reach its $16.4 trillion debt ceiling on December 31.
The Treasury Department is to begin "extraordinary measures" to buy time. Many analysts believe the government can stave the default date off into late February.
(Additional reporting by Doina Chiacu, Alina Selyukh and Richard Cowan; Writing by Alistair Bell; Editing by Will Dunham)