Gallup:

Gallup Daily tracking for the week ending April 4 finds the two major parties tied at 46% in the congressional voting preferences of registered voters nationally. In the two weeks since Congress passed healthcare reform on March 21, Democrats have tied or trailed the Republicans, after having at least a slight advantage in the weeks prior. Given Republicans’ typical voter turnout advantage in midterm elections, even Republican parity with the Democrats in the candidate preferences of registered voters could translate into significant Republican gains on Election Day. While it is too early to predict voter turnout by party this November, Republicans continue to show much greater enthusiasm than Democrats about voting in the 2010 elections.

Also note that today, 49 percent of registered voters say the representative in their congressional district deserves reelection, and 40 percent say their representative does not. In late October 2006, the split on that was 54 percent “deserves,” 33 percent “doesn’t deserve.” In November 1994, the split on that question was 54 percent “deserves,” 30 percent “doesn’t deserve.”