Most presidents affect the standing of their political parties. Ronald Reagan advanced his party's standing among young voters. So did Bill Clinton.
In his first term, George W. Bush helped Republicans equal Democrats in party identification in the 2004 exit poll -- the first time that happened since polling began.
But in his second term, Bush proved toxic to the Republican label. The Pew Research Center showed Democrats with a 51 percent to 39 percent party identification edge over Republicans in its 2008 polls.
Now Pew Research has come out with figures for 2011. They're not good news for Barack Obama and the Democrats.
The Democratic Party identification edge has been reduced to 47 percent to 43 percent. That's a 4 point drop for Democrats and a 4 point rise for Republicans since 2008.
The Pew analysts note, as if they were analyzing a growth stock, that the Republicans' numbers haven't improved since 2010. But the 2010 numbers yielded a 52 percent to 45 percent Republican lead in the popular vote for the House.
If -- and it's always a big if -- Republicans can maintain that standing in party identification, they should be in fine shape in November 2012, even with increased presidential year turnout.
It's interesting to see which groups have moved most in party identification.
As the Pew analysts note, there has been little change among blacks, who are overwhelmingly Democratic. Hispanics come in at 64 percent to 22 percent Democratic, somewhat better for the president's party than last year, when they voted 60 percent to 38 percent Democratic in House elections.
But there has been big movement among whites. In 2008, they were 51 percent to 40 percent Republican. In the first half of 2011, they were 56 percent to 35 percent Republican -- more Republican than Southern whites were three years ago.
The most noteworthy movement among whites has been among voters under 30, the so-called Millennial generation. Millennials voted 66 percent to 32 percent for Barack Obama in 2008 and identified as Democrats rather than Republicans by a 60 percent to 32 percent margin.
But white Millennials have been moving away from the Democrats. The Democratic edge in party identification among white Millennials dropped from 7 points in 2008 to 3 points in 2009 to a 1 point Republican edge in 2010 and an 11 point Republican lead in 2011.
There have been shifts of similar magnitude among whites who are low-income, who have no more than a high school education and who live in the Midwest.