Another new poll of Virginia shows an intensely competitive Senate contest looming in 2012, with former senator George Allen (R) holding the narrowest of edges over former governor Timothy M. Kaine (D).

The Roanoke College poll of likely voters gave Allen 42 percent to Kaine’s 39 percent in the contest to succeed retiring Sen. James Webb (D). Neither Allen nor Kaine is assured his party’s nomination but both are widely expected to win their primaries.

In the presidential race, the survey finds former Massachusetts governor Mitt Romney (R) leading President Obama, 45 percent to 37 percent, while Texas Gov. Rick Perry scored 42 percent to Obama’s 40 percent, less than the poll’s margin of error of plus or minus 4 percent.

The Roanoke College poll was weighted based on data from exit polls of the 2009 Virginia election, which produces a different sample — older, and with fewer minority voters — than a national presidential election year does. Washington Post assistant polling director Peyton M. Craighill ran Roanoke College’s numbers using data from the 2008 exit polls instead, and found some small differences: Kaine and Allen were tied at 40 percent, while Romney’s lead over Obama narrowed to just 1 point. Perry’s 2-point lead over Obama flipped to a 1-point deficit.

Overall, the Roanoke College results were in line with other recent polls of Virginia. A Quinnipiac University survey released in mid-September showed Allen with a 1-point lead over Kaine and Romney with a 2-point lead over Obama, both within the margin of error.

Both Quinnipiac and Roanoke College’s polls found that 54 percent of Virginians disapprove of how Obama is handling his job.