By Steve Holland

WASHINGTON (Reuters) - President Barack Obama on Wednesday met with frustrated Senate Democrats, some of whom fear the disastrous rollout of his signature healthcare law could complicate their already difficult re-election fights in 2014.

The Obama administration has weathered intense criticism since hundreds of thousands of people have seen their health insurance policies canceled because they do not meet new benefit requirements, despite Obama's pledge that Americans could keep their current plans under Obamacare.

The fallout has been exacerbated by the fact that these people cannot shop easily for insurance alternatives on the malfunctioning website, HealthCare.gov.

Obama, joined by Vice President Joe Biden, sat down with 16 Senate Democrats, 15 of them who are up for re-election next year, many of them facing competitive races.

One of the senators, Mark Begich of Alaska, issued a statement after what he said was a two-hour session. He said he expressed his frustration at the difficulties involving the website that has not worked properly since going live on October 1.

"It's absolutely unacceptable in this day and age that the administration can't deliver on the promises it made to all Americans because of technical problems with a website," Begich said.

Senate Mark Pryor of Arkansas said after the meeting: "The American people are frustrated with the White House's botched rollout of the Affordable Care Act, and I am too."

"In today's meeting, I told the president and vice president three things: 1) fix the website immediately 2) address the problems with the law and 3) hold the individuals in charge accountable for these mistakes. I won't let up until these problems are fixed," he said.

In a sign of its political potency, the rocky launch of Obamacare appeared to help Republican Ken Cuccinelli cut into the lead enjoyed by Democratic Party insider Terry McAuliffe, who won Tuesday's election for Virginia governor.

Story continues

The White House said Obama discussed efforts to ramp up communication and education outreach to consumers who have received or might receive letters about how their individual health plans might be affected.

"During the meeting, the president discussed ongoing efforts to fix HealthCare.gov and improve the experience of Americans looking to enroll in coverage," a White House official said.

The senators gave Obama "their input on existing challenges with implementation of the Affordable Care Act," the official said.

As many as 7 million Americans were expected to sign up for coverage in the first year through the online exchanges established under the 2010 Patient Protection and Affordable Care Act, according to the Congressional Budget Office. The law, upheld by the U.S. Supreme Court last year, mandates everyone have healthcare insurance coverage or pay a tax.

A significant shortfall in enrollees, particularly among young and healthy people who cost less to insure, would undermine the ability of the exchanges to work financially.

The meeting was held just before Obama left for Dallas, where he was to visit volunteers who are helping people sign up for health insurance. This is part of a push by senior officials to highlight the program in cities with the highest number of uninsured residents.

SHAKEUP AT TECHNOLOGY OFFICE

The government technology office that supervised HealthCare.gov has undergone a shakeup following the website's troubled rollout. Tony Trenkle, head of technology at the Centers for Medicare and Medicaid Services, is leaving the agency for the private sector, CMS spokeswoman Julie Bataille said on Wednesday. She said he "oversees all of our IT functions" but declined to describe his role in the website or say whether he had been asked to leave.

Obama, who routinely is engaged in political battles with congressional Republicans, is hearing complaints from his Democratic allies over the healthcare rollout. Some Democrats have joined Republicans in calling for an extension of the enrollment period for uninsured people to sign up for subsidized coverage. The administration has so far resisted.

On Capitol Hill, Senator Max Baucus, chairman of the U.S. Senate Finance Committee, said he has been disappointed to hear administration officials say they did not see problems with HealthCare.gov coming.

"When we asked for updates on the marketplaces, the responses we got were totally unsatisfactory. We heard multiple times that everything was on track. We now know that was not the case," he told U.S. Health and Human Services Secretary Kathleen Sebelius at an oversight hearing on Wednesday.

Obama has promised that the website will be fixed, with aides saying it should be operating smoothly for most people by the end of November. Many Washington political figures have urged him to express regret for saying people can keep their plans if they like them, and propose some fixes to the healthcare plan to take account of the plan cancellations.

The White House official said Obama emphasized that he shared the senators' commitment to ensuring that Americans who want to enroll in health insurance through Obamacare are able to do so in time for insurance coverage to start as early as January 1.

(Additional reporting by Susan Cornwell; Editing by Karey Van Hall, Bill Trott and Mohammad Zargham)