(Bloomberg News) President Barack Obama said he would push back against Republican attempts to alter the Dodd-Frank regulatory overhaul, in particular the Consumer Financial Protection Bureau.

"I will fight any efforts to repeal or undermine the important changes that we passed," Obama said today in remarks at the White House after nominating former Ohio Attorney General Richard Cordray to be the agency's first director. "We are going to stand up this bureau and make sure it is doing the right thing for middle-class families."

Senate Minority Leader Mitch McConnell of Kentucky and 43 other Republicans announced in May that they wouldn't vote to confirm anyone as director until changes were made to its structure, a message he repeated today. Under procedural rules in the 100-member Senate, the Republicans could block any vote.

"Senate Republicans still aren't interested in approving anyone to the position until the president agrees to make this massive new government bureaucracy more accountable and transparent to the American people," McConnell said in a statement.

The bureau, which was set up by Harvard professor and Obama adviser Elizabeth Warren, is scheduled to start work on July 21. In a posting on the White House blog, Warren criticized "trillion-dollar banks" and Republicans who oppose or want to revamp the agency.

"This agency still has enemies in Washington," Warren wrote. "And they have a plan."

Possible Senate Bid

Warren, who didn't rule out running for the U.S. Senate as a Democrat in November 2012, will return to Harvard later this year.

"That'll be the time to think about my future," Warren said today in an interview on Bloomberg Television's "Bottom Line" program.

Jay Carney, the White House spokesman, said the administration would fight efforts to weaken the agency.

"We believe that Mr. Cordray is the right person for the job and will push that forward," Carney said today at a news conference.

Consumer advocates including Robert Weissman, president of Public Citizen, back Cordray even as they express disappointment that Warren didn't get the job.

Obama "succumbed to Wall Street" in bypassing Warren, Weissman said in an interview.

"We are going to strongly support Cordray, and we want the White House to push hard for his confirmation," Weissman said. "If the Republicans indicate they will block confirmation, we want to see a recess appointment."

'Deep Concerns'

David Hirschmann, who heads the Center for Capital Markets Competitiveness at the U.S. Chamber of Commerce, said the business group has "deep concerns" about how Cordray would wield the bureau's powers.

"We will need to understand where Mr. Cordray stands on these issues," Hirschmann said in a statement.

Under the Dodd-Frank law enacted last year, the consumer bureau on July 21 will assume authorities under pre-existing laws, including the Truth in Lending Act. It doesn't inherit other powers such as the ability to supervise non-bank financial firms, including payday lenders and mortgage originators, until a director is in place.

Full Powers

Senator Tim Johnson, a South Dakota Democrat and chairman of the Banking Committee, said yesterday in a statement that he will move the nomination "as quickly as possible" so that the bureau can assume its full powers.

Senator Rob Portman, who was among the Republicans to sign the May letter, didn't rule out voting to confirm Cordray, a fellow Ohioan.

"Rich Cordray is a dedicated public servant and I will look forward to hearing his views, including on how the CFPB can be made more accountable," Portman said in a statement yesterday. "As I have said since its inception, I have serious concerns about this new federal bureaucracy."

Calls to the office of Senator Scott Brown, one of two Republicans who didn't sign the letter, weren't returned. Brown, of Massachusetts, would be Warren's opponent if she decides to run for Senate next year and wins the Democratic nomination.