Sen. Ron Johnson, one of the most vulnerable Republicans seeking re-election this year, is showing new life after a Marquette University Law School poll released Wednesday showed the incumbent trailing his rival, former Sen. Russ Feingold (D), by a 5-point margin.

The new survey shows Feingold leading Johnson 47 percent to 42 percent among registered voters, and by a narrower 48 percent to 45 percent margin among those who said they are certain to vote in November.

Related: Morning Consult’s Senate Race Rankings

For any other senator, being down 5 points would be terrible news. For Johnson, who has trailed Feingold by 11 or 12 points in each of Marquette’s last three surveys, a five-point deficit represents a silver lining on what had been a very dark cloud. Feingold led 49 percent to 37 percent in Marquette’s February survey.

Johnson, who beat Feingold in the 2010 Republican wave, still has room to grow; while only 32 percent see Johnson favorably, 36 percent of Wisconsin voters say they don’t know enough about the incumbent to form an opinion. A quarter of voters don’t know enough about Feingold, though 41 percent see him favorably.

Both candidates are trying to buck history: It has been a century since a former senator won his seat back from the candidate who beat him six years earlier. And it’s been 36 years since a Wisconsin Republican won a Senate contest in a presidential year.

At the very least, the numbers suggest Johnson — the most vulnerable senator to stick to the party line by refusing to hold hearings on President Obama’s nominee to fill a vacancy on the Supreme Court — isn’t being tarnished by his stand, yet.

The Marquette Law poll was conducted March 24-28 among 1,405 registered voters, for a margin of error of plus or minus 3.3 percentage points. The sample of 957 likely voters carries a margin of error of plus or minus 4.1 points.

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