WASHINGTON Eager to notch another year-end political victory, U.S. President Barack Obama worked to ease Republican doubts over a nuclear arms treaty with Russia on Monday.
Success on the START treaty would cap a productive period for Obama in the closing weeks of this Congress, before Republicans take control of the U.S. House of Representatives next month.
Lawmakers on Saturday repealed a 17-year-old ban on gays serving openly in the U.S. military that Obama had campaigned to end. He will sign the repeal into law on Wednesday.
Last week, Congress passed a sweeping extension of Bush-era tax cuts that Obama said would boost U.S. growth and jobs.
The gains are helping to restore Obama's momentum, after he appeared seriously weakened by November elections in which voters slammed his Democrats.
START is Obama's last big remaining legislative priority before he heads to Hawaii to join the first family for their year-end vacation.
"The White House believes that before Congress leaves town the Senate will ratify the New START treaty," White House spokesman Robert Gibbs told reporters.
He said the president was working the phones from the White House to persuade senators to support the treaty before lawmakers head home for their Christmas holidays. He hinted strongly that Obama would hold a news conference on Wednesday or Thursday.
Russia warned U.S. lawmakers on Monday that any changes to the treaty, signed by Obama and President Dmitry Medvedev in April, could kill the pact.
Gibbs would not say whether he believed Republicans were trying to prevent START ratification in order to deny the president another legislative victory, as some Democrats suspect.
But he said Republican complaints over a preamble to the treaty on U.S. missile defense was at odds with their other complaint that they had not had enough time to read the pact.
"It's a little vexing to figure out how somebody can say in largely the same breath that they're concerned about what the preamble does to missile defense, but they haven't had enough time to look at the treaty," he said.
In the Senate, debate on the strategic nuclear arms treaty entered its sixth day. Democrats have moved to force a final vote no later than Thursday and need nine Republican senators to back ratification.
They are pushing to pass it before the new Congress takes office in January, when Democrats' Senate majority will be reduced from 58-42 to 53-47. The treaty needs 67 votes for approval in the 100-member Senate.
"START's going to be voted on before Congress leaves town," Gibbs said. "Because of ... the importance to our foreign policy and to reducing the number of deployed nuclear weapons that each of these two countries has pointed at each other, it's important to get this done now."
(Editing by Stacey Joyce)