Mr Obama held a clear-the-air meeting at the White House with party leaders, whose frustration with the administration had been simmering for months.
He promised to provide his full support from now until the midterm elections in November, when the entire 435-seat lower chamber will be contested.
Anger among Democrats had boiled over after Robert Gibbs, the White House press secretary, said on national television last weekend that the party's 75-seat majority could be overturned at the polls.
Nancy Pelosi, the Speaker of the House, was said to be "nuclear mad" about Mr Gibbs's comments.
An aide said she referred to the remarks as "friendly fire," and called them "very damaging".
Louise Slaughter, a member of Democratic leadership, said: "It was an absolutely ridiculous thing for him to say. We didn't appreciate it."
The row came as the president's popularity continued to slide, with voters expressing declining confidence in his handling of the economy.
Obama's job approval rating down three points to a new low of 44 per cent. Those who approved of his handling of the economy dropped five percentage points in a month to 40 per cent.
Mr Obama on Thursday travelled to Holland in Michigan, where $472 million from last year's $800 billion stimulus has been spent, principally on new electric vehicle battery factories.