Senate Minority Leader Mitch McConnell (R-Ky.) takes questions from members of the press after speaking at Whayne Supply headquarters while campaigning during a two day bus tour of eastern Kentucky Aug. 7, 2014 in Corbin, Ky.
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New polls show party lines darkening for 2014

Updated

With the 2014 campaign season making a turn into the autumn home stretch, three new state polls by NBC News/Marist shows Republican Senate candidates in Arkansas and Kentucky improving their standing with voters while the Democratic lead in Colorado’s Senate race maintains.

The change since the last time the poll was taken, in May, is most pronounced in Arkansas, where Democratic incumbent Senator Mark Pryor’s 11-point lead among registered voters has dwindled to a tie with Republican challenger Rep. Tom Cotton. Cotton’s number has grown only slightly, but Pryor’s decline coincides with the addition of two new candidates since May (a Libertarian and a Green Party candidate) and some growth in the number of undecideds. 

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In a showdown between two former congressmen running for Arkansas governor, Republican Asa Hutchinson is ahead of Democrat Mike Ross among likely voters, 48% to 39%. 

The addition of a third candidate also corresponds to a decline in support for Alison Lundergan Grimes, the Democratic challenger to Republican Senate Minority Leader Mitch McConnell in Kentucky. McConnell’s 46% to 45% lead over Lundergan Grimes among registered voters in May has extended to 45% to 38%, with 9% supporting Libertarian David Patterson.

This is the first independent poll to be conducted entirely after McConnell’s campaign manager resigned in proximity to a political payoff scandal.

Democratic Colorado Senator Mark Udall’s 8-point lead over challenger Cory Gardner among registered voters is essentially unchanged since July. Democratic Governor John Hickenlooper also leads his Republican challenger, Bob Beauprez, 43% to 39% among likely voters, with another 5% going for Libertarian Matthew Hess.

In both Arkansas and Kentucky, President Obama’s approval rating is 31%, but it is higher in Colorado at 39%.

All three polls found that more people would like to see “A Republican majority in both the House and Senate as a check on President Obama in his final two years” than “More Democrats in the House and a Democratic majority in the Senate to send a message to Republicans that they need to work with President Obama, not against him.” Responses differed by an 11-point margin in Arkansas, and a 9-point margin in Kentucky, but were more evenly divided in Colorado at 41% to 39%.

Approval of Congress was in the 20s in all three polls, with only 19% of Colorado respondents approving of Republicans in Congress.

NBC News senior political editor Mary Murray suggests in his analysis that Republicans extending leads in red states (Arkansas, Kentucky) and Democrats preserving leads in blue states (Colorado) could indicate diminishing likelihood of a Republican wave crossing traditional party lines.

New polls show party lines darkening for 2014

Updated