Now, some bankers, their lobbyists and their Republican allies on the Senate banking committee reportedly would like nothing better than to keep Ms. Warren off the powerful bank panel — where she could do the most harm to the status quo, and the most good for the country.

Republicans have opposed Ms. Warren before, notably in their successful fight in 2011 to prevent her from becoming the first director of the Consumer Financial Protection Bureau, the agency that was her brainchild and that is arguably the most important part of the Dodd-Frank financial reform.

The Senate majority leader, Harry Reid, who assigns freshman senators to the committees, should not let them get their way again.

As a bankruptcy expert, Harvard law professor and former chairwoman of the Congressional Oversight Panel charged with overseeing the bank bailouts, Ms. Warren knows what makes banks work and what makes them fail. She would join the banking committee as the fight intensifies over the Volcker Rule, a provision of Dodd-Frank she has supported that, if done right, would curb speculation by banks.