First, I recommend an excellent post by Matt Yglesias about the relative lack of importance of Mitch McConnell in the new scheme of things. The only thing that I'd add is that the press generally overrates the importance of Senate party leaders to begin with, so start with that, and combine with what Yglesias says about the partisan context, and there you have it.
Second, over on the House side, almost nothing the minority party does is very important, but nevertheless I'm glad to see Nancy Pelosi sticking around for Minority Leader because...well, because I get to say "told you." Me, on October 7:
I've seen some outsider speculation about what Nancy Pelosi would do if the Democrats lose the House, but so far I don't think I've seen any actual whispers against her that seem to come from inside her caucus. As far as I can tell, she can have Minority Leader if she wants it (and my guess is that she will, especially if modest gains in 2012 would put her back in the big chair).One of the easiest calls I've made. Pelosi is a very, very good pol, and while I'm not a reporter and have no inside information, nothing has been reported that sounds even remotely like unhappiness with her. Yes, I know that some of the conservatives members of the caucus engage in a little liberal-bashing at her expense, but they and everyone know that the Democrats will have a liberal as their Leader in the House, and whoever that is will be demonized by GOP attackers.
Besides, in their hearts, I have no doubt that Pelosi isn't even close to the top of the list of who House Democrats really blame for the 2010 cycle. My guess is that #3 on that list is Barack Obama; #2 is Rahm Emanuel; and, by far, lapping the field, #1 is the United States Senate.