In Wisconsin, embattled 18-year incumbent Russ Feingold hangs by a thread in the face of a tough Republican challenge and growing voter discontent with his failed, costly, partisan agenda.  The New York Times’ Jeff Zeleny reports:

Wisconsin is more divided politically than it is often perceived, given its well-known progressive streak. But Mr. Feingold’s own polling — in line with the judgment of independent analysts — shows him in a unexpectedly tough race against a neophyte Republican opponent. His challenger has so far spent three times as much as he has, the economy remains lackluster and Mr. Feingold is facing disillusionment with Democratic policies. Party leaders, who had considered his seat something of a firewall to protect control of the Senate, now see it as a bellwether that could signal whether other once-safe seats are vulnerable. The main Republican challenger, an Oshkosh millionaire business executive named Ron Johnson, has never run for public office. Yet that may be one of the brightest credentials a candidate can carry these days…To win control of the Senate, Republicans need to pick up 10 seats, nearly all of which must come from territory held by Democrats. But there are now enough competitive seats that Republicans could let two opportunities for victory slip away, providing a bit of breathing room for some untested candidates. “A few months ago, we wouldn’t have been able to say that,” said Senator John Cornyn of Texas, chairman of the National Republican Senatorial Committee, who warns against overconfidence. “We have more options than we ever expected.”