Obama has warned what Republican congressional leaders would do if they take back Congress, but it's been rare to see the president reference a Republican challenger to a major Democratic incumbent like Murray.

"I could see him saying, 'Here's certain provisions I might modify,'" Obama added. "But just to say we don't need it when we almost had a complete financial meltdown?"

Democrats have put pressure on GOP candidates to say whether they would repeal the Wall Street reform or the healthcare reform bill Obama signed into law earlier this year.

Democrats believe that highlighting popular elements of those bills — threatened by GOP repeal — will work to their advantage in this fall's elections.

"We need to repeal that bill," Rossi said on an ABC News webcast in late July.

Rossi's position on Wall Street reform is the same as many other Republican leaders, who had opposed the financial regulatory bill.

“Today Washingtonian witnessed how quickly this politics of hope can turn to the politics of desperate partisan attack.  Rather than explaining why Senator Murray’s economic policies have failed to create jobs while they exploded the deficit and the debt, President Obama chose instead to attack Dino Rossi," said Jennifer Morris, the communications director for Rossi's campaign. "If someone as eloquent as President Obama can’t defend her 18-year record of spending, taxing, and growing government, who can?  It’s clear Washington needs Dino Rossi in the Senate to get the economy moving and keep spending under control.”