Despite opposing cloture on a previous cap and trade bill, Sen. Sherrod Brown (D-OH) says that--whether he supports the underlying bill or not--he won't support a filibuster of climate change legislation this Congress.

"I'm not going to be part of a filibuster on climate change," Brown told me today. Brown voted against ending debate on the Lieberman-Warner bill in 2007, but he says he did that because the bill had no real chance of making it to the floor, and opposing cloture was his way of expressing his objection to aspects of that legislation.

"I was not blocking the bill from having a hearing on the floor, because it wasn't gonna get to that," Brown said. "I wanted to show that I don't support this bill unless you take care of American manufacturing."

Brown's declaration is significant if not entirely unexpected. A number of Democrats from coal, oil, and manufacturing states have been either resistant or outright opposed to significant action on climate change in recent years. But Democrats are more aware of that fact than ever. And as critical as some liberals and environmentalists were of a number of pre-vote concessions, the Waxman-Markey bill, which recently passed in the House, was designed in collaboration with just those sorts of Democrats--and crucially, Democrats from states whose senators have been on the fence on the issue in the past.

They've noticed the difference. "I thought that Waxman was unbelievably adept," Brown said.

But that doesn't mean the process will be easy. Some key questions remain to be answered, such as: What language will the Senate Environment and Public Works Committee use as a legislative starting point? How closely will that chamber's process mimic the Waxman-Markey process? And will Democrats--even those who oppose the final bill--agree to oppose a GOP filibuster?

On that last question, Brown is saying yes.