A Senate committee on Wednesday approved a bill aimed at reforming the derivatives market, moving the Senate one step closer to passing sweeping regulation over the $450 trillion derivatives market.

The Senate Agriculture Committee approved the legislation by a vote of 13 to 8, with one Republican, Charles Grassley, breaking ranks to vote with Democrats.

The measure, part of the Democrats push to crack down on Wall Street, is expected to be merged into a broader bill from the Senate Banking Committee. A full Senate debate is expected by next week.

Its passage through the committee was a first test of how strongly Democrats are willing to push reform -- and how easily Republicans may be prepared to play ball.

(Editing by Andrew Hay)