Russ Feingold (D-inc): 41 (45)
Ron Johnson (R): 52 (43)
Undecided: 7 (12)
Tom Barrett (D): 41 (38)
Scott Walker (R): 50 (45)
Undecided: 8 (17)
This poll has already been so thoroughly teased that there's not much shock value left to it. Also, it shouldn't be a surprise that PPP finds Ron Johnson with a lead over Russ Feingold, considering that the last five Rasmussen polls have done so (with no one else to give an alternative read in the last couple months). But a double-digit lead is definitely an attention-getter. The question seems to be whether the race has really moved in Johnson's direction lately (which Rasmussen also would suggest) or if PPP caught a bad bounce on this one... either way, it's clear Feingold is in a bad position and that complicates the Senate picture (although Wisconsin always seemed to me to be the weakest of the three so-called "firewalls" -- and now it's seeming weaker than Colorado, Illinois, or Nevada, considered by the CW to be on the wrong side of the firewall).
There's a whole lotta enthusiasm gap going on with PPP's likely voter screen here, maybe more so than any poll we've seen this cycle, with Barack Obama's approval down to 41/54 (compared with 2008 results, where he won 56-42). Feingold's approval is down to 40/53, which contrasts with Johnson's 46/34 faves. Based on that difference, it seems like even if Feingold weren't running into a stiff headwind from the national climate this would still be a very close race, as Feingold has tended to run close races in the past and has been seemingly searching in vain for an ad strategy that really defines the hard-to-pin-down, generic-wealthy-businessman Johnson.
While we think this particular poll overstates Feingold's likely doom, there's no doubt that this race is properly considered a Tossup (which we're moving from Lean Democratic).
UPDATE: Talking Points Memo today makes reference to Democratic internal polling just prior to last week's primary (sorry, no link to an actual polling memo, which would certainly be helpful) that had Feingold leading 48-41 among "all voters" and 47-43 among "those definite to vote."