In the last couple of years, the Blue Dog caucus—of which Rep. Jim Matheson, D-Utah, is a member—has become a strong voice within the Democratic Congressional caucuses, especially the House. Among the successes for their fiscally-conservative politics was forcing a number of compromises on the healthcare reform bill and essentially killing the single-payer proposal.
Now, however, the frustration with the overall Democratic Congress is haunting many of the Blue Dogs in mid-term elections—even those who voted against most of the things their constituents are angry about (or, in cases like TARP, were pushed by a Republican administration). In a detailed analysis on the FiveThirtyEight blog, Tom Schaller draws the conclusion that many of the expected Democratic losses this fall will be from the "more conservative" %uFFFDelement of the Democratic caucus. Even if they are not Blue Dogs in name, they are probably closely aligned with the Blue Dog politics and account for the Blue Dog strength.
Mostly, those losses will be to Republicans in districts where voters would have voted almost any Democrat out of office, regardless of their voting record. A good portion of them have already fought off primary challenges—such as Sen. Blanche Lincoln in Arkansas—which cost money and forced them to deal with issues they would prefer not deal with, including having to justify their reasoning for voting against healthcare reform to a liberal voting bloc within their party. Yes, this happened with Matheson, as well, who had to win a primary against Claudia Wright, so he could be lumped into this "threatened" Blue Dog group. But, right now, Matheson still has plenty of money and, unlike many of his Blue Dog counterparts who are facing centrist Republicans, he is facing the strongly conservative Morgan Philpot.
Thus, the Blue Dogs will not be replaced by more liberal Democrats. Instead, the Republicans could very well seize control of the House by toppling centrist Democrats, generally with centrist Republicans. The upshot of this, Schaller says, is that the House Democratic Caucus will be more liberal than it is now. It's logical to assume that the Republicans will be less conservative, although the influx of Tea Party candidates could make it seem even more radically conservative.
What does this mean for Matheson? No matter what, he will still be able to crow about his Blue Dog philosophies, but in the House he will not be able to leverage them as well among Democrats. On the flip side, as one of a smaller group of centrist Democrats, he will become more popular with Republicans as they try to cobble together a strong voting majority. If the Republicans take control of the House, this could actually make him more valuable to Utah (hello, earmarks) then he would be if the Democrats hold the House. (Note: I requested comment this afternoon from Matheson on Schaller's blog, but have not heard back. If he does respond, I will add his thoughts about the impact).