LAS VEGAS (AP) — President Obama and Democratic leaders sought to soothe relations with the party’s disgruntled left wing Saturday in advance of elections in which Republican gains could upend the White House agenda.

‘‘Change hasn’t come fast enough for too many Americans. I know that,’’ Obama said in a surprise video appearance to liberal activists and bloggers at Las Vegas convention. ‘‘I know it hasn’t come fast for many of you who fought so hard during the election.’’

In a year when Democrats are expected to lose seats in Congress, party leaders have grown increasingly concerned with malaise running through the left wing. Liberals who helped elect Obama in 2008 have grown disenchanted on issues from the ongoing wars in Iraq and Afghanistan to the failure to create a government-run insurance option in the health care overhaul, and many believe the White House has been too accommodating with Republicans.

In his remarks to the annual Netroots Nation gathering, the president said the combat mission in Iraq would soon end, and that the administration is working to repeal the military’s ‘‘don’t ask, don’t tell’’ policy for gays and close the U.S. prison for terrorism suspects at Guantanamo Bay.

‘‘In ways large and small we’ve begun to deliver on the change you fought so hard for,’’ Obama said.

‘‘We cant afford to slide backward. And that’s the choice America faces this November,’’ he added. ‘‘Keep up the fight.’’

Conservative bloggers and activists were meeting in a hotel nearby in what amounted to a rival convention, where Nevada Senate candidate Sharron Angle, a tea party favorite, called for support to oust Senate Majority Leader Harry Reid.

Obama’s message was amplified by Reid and House Speaker Nancy Pelosi, who called for setting aside differences to elect Democratic candidates.

Reid earned a burst of applause by telling the Netroots Nation crowd, ‘‘I know that there are times, I’m told, I get on your nerves.’’

He said there might be differences from time to time but ‘‘let’s all understand this county would be in a lot more trouble if we weren’t around.’’

House Speaker Nancy Pelosi, who introduced Obama’s video, asked the crowd to recognize what’s been achieved in Washington since Obama’s election and not let differences cause a political fissure.

The day after the election ‘‘we want to have no regrets,’’ Pelosi said.

Hundreds of activists and bloggers applauded warmly after the Obama video ended, but some were not appeased.

The video ‘‘doesn’t really change my views. I’m still waiting for action,’’ said Matthew Filipowicz, 33, a cartoonist and comedian from Chicago. ‘‘Words only do so much.’’

Pelosi received a standing ovation from most of the people in the cavernous, partly filled auditorium at a Las Vegas casino.

When asked a question about the military policy on gay servicemembers, someone shouted from the audience.

‘‘Your impatience is justified,’’ Pelosi responded.

Just two days after Senate Democrats gave up plans to attempt to pass an energy bill that caps greenhouse gases blamed for global warming, Pelosi said ‘‘this is not an issue the Senate can walk away from.’’

The plan was a priority of Obama, who had hoped to add a climate bill to his list of legislative successes.

‘‘We’ll welcome whatever the Senate can pass to reduce our dependence on foreign oil,’’ Pelosi said. ‘‘Sooner or later this has to happen.’’

Reid lamented GOP opposition to the bill and said new, albeit trimmed down, legislation would be introduced. He has said previously it would crack down on oil giant BP PLC, boost energy efficient homes and provide incentives to convert many of the nation’s large trucks from diesel fuel to natural gas.