In an email announcement today the Elizabeth Warren campaign said they raised $6.9 million since January 1st for her Massachusetts Senate campaign. That figure is well in excess of the $3.4 million her opponent, incumbent Republican Scott Brown, pulled in last quarter, although the Brown campaign does have a significant amount saved up from earlier fundraising.

If this fundraising pace continues, this Massachusetts senate campaign could easily end up the most expensive Senate campaign this season, if not one of the most expensive Senate campaigns of all time. The recent polling shows that the race is very close, which is partly why it has attracted so many donors on both sides.

This contest may serve as an interesting test of whether incumbency is worth a much now as it used to be. According to Gallup Massachusetts is the state with the third highest percentage of Democrats / Democratic leaning voters.  If Brown weren’t an incumbent, in a normal Presidential election environment he probably wouldn’t stand a chance running as a Republican. If polarized and increased party discipline in Congress is causing more Americans to vote straight party line, Brown will be in real trouble. Given the massive Democratic registration advantage Brown is going to need to make this a race about two people instead of two parties.