With the congressional elections fast approaching, President Barack Obama acknowledged Saturday that the hope and energy he stirred during his presidential campaign may have faded in the face of a grinding economic crisis.

"We're doing the grinding, sometimes frustrating work of actually delivering change. I know it can be discouraging," Obama told a crowd of 10,000 at an energetic rally at Boston's Hynes Convention Center.

Obama came to Boston to campaign for his friend and political ally, Massachusetts Gov. Deval Patrick, who is struggling to overcome the anti-incumbent mood that has swept across the country during this election season.Obama said Patrick's opponent is banking on the same strategy as national Republicans.

"They figured they could ride people's anger and frustration all the way to the ballot box," said Obama, dressed more casually for the weekend rally, in a sport coat but no tie.

With just over two weeks until election day, Obama has been campaigning coast to coast, raising money for candidates and looking to energize dispirited Democratic voters. While the White House says it still believes Democrats will retain control of the House and Senate, a sputtering economy leaves the political climate perilous for the president's party.