Poll: Tea Party threat to Allen minimal

While it suggests an early edge for Allen, it's largely a test of name recognition at this stage. Radtke is known by just 21 percent of Virginia Republicans, while Marshall stands at just 25 percent name ID. 

Still, Allen's Republican challengers have at least some room for growth. Asked if they preferred a generic "more conservative" option instead of Allen, 25 percent of Virginia Republicans answered yes. Another 52 percent would stick with the former senator. 

"That's better than most long time GOP politicians are faring against hypothetical foes to the right," pollster Tom Jensen writes. "Before he retired, we found Jon Kyl under 50% against a 'more conservative' alternative and Bob Corker (Tenn.) actually trails a generic challenger to his right. So for Allen to have a 27 point lead on that measure is significant."

The greatest question in the primary for Allen will be the size of the Republican field. Should it swell to four or more candidates, the path to the nomination for Allen would likely be eased as any conservative opposition would be split among Allen's challengers. 

An earlier PPP survey showed Allen in a dead heat with Democratic National Committee Chairman Tim Kaine in a hypothetical general election match-up. Virginia Democrats are anxiously awaiting Kaine's decision on a run, which is likely to come by next week.