(Recasts with Obama's comments)
By Thomas Ferraro and Richard Cowan
CAMBRIDGE, Md., Feb 14 (Reuters) - President Barack Obama sought on Friday to ease strains with his Democratic allies in the U.S. Congress, who are fearful they could face election consequences from the botched rollout of the president's signature healthcare law known as "Obamacare."
Speaking to House of Representatives Democrats during their three-day retreat, Obama cited an increase in the number of people signing up for insurance coverage under Obamacare as evidence that the law's implementation was going more smoothly after a troubled start.
Republicans, who have denounced Obamacare as an unpopular disaster, have put the issue at the center of their strategy for November's congressional elections.
But Obama has touted the administration's progress in ironing out the glitches. At the retreat, he predicted that the 2010 Affordable Care Act will be seen by Americans in five to 10 years as "a monumental achievement."
"We now have well over 3.5 million people who have signed up and are getting insurance through the marketplaces for the first time," Obama said.
All 435 House seats along with 36 of the 100 Senate seats are up for grabs in the elections.
Republicans are expected to retain the House, which they now control 232-200 with three vacancies. They hope the Obamacare issue will help them seize control of the Senate, which Democrats hold 55-45.
The troubles with Obama's healthcare law have weighed on the president's popularity. His approval rating now stands at 43 percent, and Democrats worry that Americans' concerns about the health law could cost them support in their districts.
Traditionally, presidents have seen their party lose seats in congressional elections during their second terms, largely due to voter fatigue with incumbents.
Since 1946, when a president's approval rating was below 50 percent in such elections, his party has lost on average 36 House seats, according to the Gallup polling firm. When it is above 50 percent, they lose on average 14 seats, Gallup said.
The healthcare issue was an important topic at the Democratic gathering at a waterfront resort. Before Obama spoke, the Democrats heard during a closed session from Ari Goldmann, a 32-year-old independent contractor and waiter who lives in Washington.
A Democratic aide said Goldmann told the lawmakers he was "beyond thrilled" when he was able to get health coverage under Obamacare after his insurance company told him it was canceling his plan.
Democrats hope to circulate more such stories in the months ahead as they scramble to win public approval of Obamacare and boost their election prospects.
At a closed-door portion of his meeting with Democrats, another party aide said Obama told the gathering that "underlying policies in the (healthcare) program are working, but of course there are glitches. We are working through these things."
Obama also discussed his legislative agenda for this year, including a push to raise the minimum wage and renew expired jobless benefits for nearly 2 million Americans.
Representative Debbie Wasserman Schultz of Florida, who chairs the Democratic National Committee, underscored her party's support of the president's efforts.
She declined to say, however, if it will be enough for Democrats to somehow win back the House.
"We are not making predictions," Wasserman Schultz said. "We are focused on making sure that when it comes to giving people opportunities to climb the ladders of the middle class, that voters understand that Democrats have their backs."
Representative Joseph Crowley of New York made reference to the snowstorm in the area when he introduced Obama at Friday's gathering. Crowley said it had been a "marvelous two days despite the weather and the odds against us." (Reporting by Thomas Ferraro and Richard Cowan; Additional reporting by Steve Holland and Susan Heavey; Editing by Caren Bohan and Jonathan Oatis)