The balance in the 2014 race for a majority in the Senate seems to have shifted -- toward the Republicans. Two polls released today showed Louisiana Democratic incumbent Mary Landrieu trailing Republican challenger John Cassidy and New Hampshire Democratic incumbent Jeanne Shaheen running even with former Massachusetts Sen. Scott Brown.

Here is how Republicans are faring in seven seats that are up in states carried by Mitt Romney. I've shown the Real Clear Politics averages or, when that wasn't available, an average from the two most recent public polls (an asterisk means there wasn't an RCP average available). Following that is the most recent public poll and the polling firm which produced it. And I've added the Gallup 2013 Obama job approval numbers for each state, rounded off to integers.

In each comparison, the best known Republican candidate’s percentage is listed first.

State Poll average Most recent public poll Polling firm Obama job approval rating Alaska 40-47* 39-50 Hays 33 Arkansas 40-40 37-36 Arkansas Poll 35 Louisiana 42-45* 44-40 Rasmussen 40 Montana 52-35* 52-35 PPP 33 North Carolina 45-41 47-40 Rasmussen 43 South Dakota n/a n/a No polling since Sept. 32 West Virginia 48-38* 50-36 PPP 25

Two Republicans seem to have clear leads in the open seats in Montana and West Virginia. You can probably add the open seat in South Dakota to that list. In Arkansas, Louisiana and North Carolina, Democratic incumbents are well under 50 percent and in some polls are trailing Republicans. It's highly unusual for an incumbent senator to run behind in a poll and a danger sign for an incumbent to poll 50 percent. Only in Alaska does the incumbent Democrat, Mark Begich, have a clear lead; but the leading Republicans, Mead Treadwell and Dan Sullivan, do not have high name identification, and the most recent poll was conducted in August, before the Obamacare rollout. Obviously Democrats are in serious danger of losing six of these seats and not in a strong position in the seventh.

Two months ago, not many analysts were paying much attention to the possibility that Republicans might win Senate seats in states carried by Obama in 2012. Now many are. The following numbers show why.

State Poll average Most recent public poll Polling firm Obama job approval rating Colorado 42-46* 42-46 PPP 42 Iowa 39-42* 40-43 Quinnipiac 42 Michigan 39-38 37-35 Rasmussen 48 New Hampshire 42-46 44-44 Purple Strategies 45 Virginia 29-50 37-51 Rasmussen 46

There are more undecideds in the open-seat races in Iowa and Michigan than in the races involving incumbent Sens. Mark Udall and Shaheen in Colorado and New Hampshire, respectively. Only Sen. Mark Warner in Virginia has a significant lead and beats the 50-percent mark, though not by much. Obama 2013 approval numbers are higher here than in the 2012 Romney states listed above, but are all still below 50 percent.

In many Senate race cycles, almost all the close races fall to one party. Based on these numbers, the best result for Democrats would be to lose 3 seats and the worst case would be to lose 11. So the Senate could be anywhere from 52-48 Democratic to 56-44 Republican. The numbers right now look favorable for Republicans, but they could change — and they don’t take into account Republicans’ demonstrated capacity to nominate unelectable candidates in winnable races.