By Lisa Lambert

WASHINGTON (Reuters) - Concerns about coordinating U.S. derivatives regulation with that of other countries dominated a Senate committee's hearing on Thursday to consider two nominees for seats on the Commodity Futures Trading Commission.

Members of both parties asked the nominees, Chris Brummer, a Georgetown University law professor, and Brian Quintenz, an investment firm founder who once worked for a Republican Representative, about cooperation with other countries during the Agriculture Committee hearing.

The committee will vote on the nominations in a separate business meeting. If approved, the nominations then go to the full Senate.

The CFTC oversees the U.S. derivatives market and recently gave swap dealers an extra month to comply with a new cross-border rule on collateral for uncleared swaps, after Asia's market froze from uncertainty about the changes. The European Commission announced this summer it was delaying its implementation of similar rules.

Both Brummer and Quintenz spoke of the need to build strong relationships with other countries. But Brummer emphasized the U.S. role in leading rulemaking.

"Overall, I think that it's hard...to lead if you don't lead by example. I think if you want to have a cross-border regulatory environment that is high quality then the United States should commit to the highest standards and find those who are like-minded," he said.

Meanwhile, Quintenz worried firms could exploit timing gaps between different countries' rules implementation for financial gain, calling it "regulatory arbitrage."

"Someone does have to go first but I don't believe that's the full analysis," he said. "I believe the full analysis is: after you go first how long will it be until all the jurisdictions move and what is the size of the regulatory arbitrage you're creating? And once other jurisdictions move will there be regulatory arbitrage going forward?"

Republican Senator Thom Tillis said that in the current situation "it's almost like we're being penalized for good behavior."

"We're on time. Some of the other key players are not...Our banking industry is suffering as we move forward with regulations that make us globally make us un-competitive," he said.

Separately, at a speech on Thursday, CFTC Chairman Timothy Massad said he had been assured by European counterparts that their delay in implementing their swaps margin rule would be short and he hoped it would be in place by March 1. He added the CFTC will explore actions it could take if the delay stretches on longer.

(Editing by Peter Cooney and Andrew Hay)