Senator Scott Brown portrayed himself as the model of a modern moderate in last night’s Massachusetts Senate debate, reminding listeners of the many bipartisan positions he has taken since filling Teddy Kennedy’s seat. And his opponent, Elizabeth Warren, had the strongest possible retort: it doesn’t matter.

Because Mr. Brown is a Republican, his presence in Washington would put the party that much closer to control of the Senate. If re-elected, he would almost immediately vote to make Mitch McConnell either the majority leader or the minority leader, depending on how the party does. And that is a vote for continuing an unprecedented pattern of obstruction and filibuster, led by Mr. McConnell, that has made the current Congress one of the least productive in history.

“At the end of the day this race may be for control of the Senate,” Ms. Warren said. “Senator Brown can’t have it both ways. He’s out there raising from Republicans all around the country, saying if you give me money and I win, it means the Republicans can take control of the United States Senate.”



Based on his initial remarks last night, Mr. Brown apparently wants the race to be about whether Ms. Warren ever claimed to be a Native American. But running in a largely Democratic state, Ms. Warren can move past that pettiness and cast the race in far larger terms unavailable to swing-state Democratic candidates like Claire McCaskill of Missouri or Tammy Baldwin of Wisconsin. The Senate is at stake, and especially if Mitt Romney wins the White House, one or two votes in the Senate could make all the difference. A Republican Senate could mean repealing health care for the uninsured, rejecting a deficit plan that includes tax hikes on the rich, and a Supreme Court that moves more emphatically to the right.

As Ms. Warren pointed out, Mr. Brown hasn’t really been that moderate. He voted against Elena Kagan for the Supreme Court, using the flimsy excuse that she lacked judicial experience and temperament. He has refused to support raising taxes on the rich, citing the same phony job-creator line used by Mr. McConnell, Mr. Romney and the right wing of the party.

But even when he votes for sensible bills like the one this week that would create a job corps for military veterans, he is overwhelmed by other members of his party who routinely kill them. (Republicans filibustered the veterans bill on Wednesday.) As Ms. Warren pointed out, Mr. Brown’s presence could give those Republicans control of every Senate committee. She cited the example of James Inhofe of Oklahoma, who has said global warming is a hoax, yet would take over the Senate Committee on Environment and Public Works, but there are many others.

Ms. Warren could rattle voters across Massachusetts with the prospect of Chuck Grassley of Iowa taking over the Judiciary Committee, John McCain taking over Armed Services, Orrin Hatch taking over Finance, or Jeff Sessions taking over Budget. The Massachusetts race could be as important as the national race, if she decides to make it so.