Enter Warren. The former Harvard professor who crafted the Consumer Financial Protection Bureau ran headlong, as so many Obama initiatives have, into the brick wall of the Republican Senate. Her contentious run-ins with Republicans overseeing the new agency made her a hero in liberals' minds while simultaneously eliminating any hope she ever had of overcoming a filibuster when she was nominated to lead her own creation. Instead, Democrats urged her to run against Brown. One outside group, the Progressive Change Campaign Committee, bundled more than $435,000 for her campaign, more than $200,000 of that amount before she had even left the administration. In short, Warren has become the outlet for liberal frustration with the administration. They view her as a fighter who stands for liberal causes and draws stark contrasts with Republicans -- exactly what they complain the administration has not done. As an added bonus to liberals looking for a champion, Warren is proving an adept campaigner. She raised more than $3 million during her first six weeks on the trail, and she's drawing huge interest inside the state; as my colleague Julie Sobel pointed out a few weeks back, Warren's first forays around the state have drawn standing-room-only crowds. Warren attracted 1,000 people to a campaign rally in Roxbury, and she even got 500 folks to show up in Pittsfield, hardly the same audience as the liberal enclave of Cambridge. She is, all things considered, most certainly not like Martha Coakley, the lackluster Democrat Brown defeated in 2010. Republicans point out, rightly so, that there's a difference between Democratic voters and liberals: Not all Democrats are liberal. That's especially true in Massachusetts, where there are still divisions between the Cambridge liberals, the Boston machine and the more culturally conservative blue collar western part of the state. Republicans have to drive a big wedge between Warren and the more conservative voters who crossed over to send Brown to Washington in the first place. They won't succeed, however, in driving a wedge between Warren and her national fan base. The left will work hard and turn out for President Obama's re-election bid, but those who drive the activist/blogosphere base see in Warren what they want to see in their party as a whole.