WRAPUP 1-US senators hit at core of Obama financial reforms

* Senators question Fed as "systemic risk" regulator

* Dodd signals support for financial product agency

* House committee hearing later Thursday

By Kevin Drawbaugh

WASHINGTON, June 18 (Reuters) - Senior U.S. lawmakers launched an assault on Thursday on the centerpiece of the Obama administration's financial reform plan -- giving the Federal Reserve new power to police broad risks in the economy.

"I do not believe we can reasonably expect the Fed or any other agency to effectively play so many roles," said Sen. Richard Shelby, the top Republican on the Senate Banking Committee.

A day after President Barack Obama unveiled the plan, Treasury Secretary Timothy Geithner was on the defensive as he testified before the committee, fielding questions about giving the Fed authority to be the "systemic risk" regulator.

Geithner urged Congress to act fast on regulatory reform. "We may disagree about the details, and we will have to work through those issues. But ordinary Americans have suffered too much; trust in our financial system has been too shaken; our economy has been brought too close to the brink for us to let this moment pass," Geithner said. (For story, please see [ID:nN18267826])

Congressional debate got under way with little reaction from Wall Street. The S&P 500 index .SPX rose less than 1 percent at midday.