Our state-by-state round-up of polls on this year’s Senate races so far supports the view that the Republicans face a challenging year. Some GOP incumbents are clearly showing vulnerabilities and others, while ahead, are looking at races that seem more competitive than a couple of months ago.

Be sure to read our Election 2008 overview of the battle for the Senate.

– **Maine:** Republican Sen. Susan Collins still has a 52 percent to 42 percent lead over Democratic challenger Tom Allen, although that is down from the 16 point advantage she had a month ago, according to a Rasmussen Reports poll conducted May 14. The margin of error is 4.5 percent. Collins is viewed favorably by 70 percent of voters compared to 29 percent with a negative view, and Allen is viewed favorably by 58 percent compared to 35 percent. Collins has the backing of 74 percent of conservatives, 55 percent of moderates and 27 percent of liberals. Allen draws on the support of 71 percent of liberal voters, 36 percent of moderates and 20 percent of conservatives.

– **Kansas:** Two-term Republican Sen. Pat Roberts has a 50 percent to 42 percent lead over his Demo critic challenger, Rep. Jim Slattery. Roberts had looked like a runaway favorite for re-election as Democrats scrambled to find a credible challenger, but they appear to have had at least some success by Slattery’s decision to get into the race. Roberts is viewed favorably by 60 percent of voters compared to 34 percent who have negative views, while Slattery’s numbers are 46 percent favorable to 38 percent unfavorable with 17 percent not sure. Both are tied at 46 percent for the support of moderate voters.