George W. Bush’s electoral architect, Karl Rove, devotes his latest Wall Street Journal column to the possibility that the flagging Obama administration could create electoral problems for even more Democrats than one might typically expect in the sixth year of a presidential administration.

For months it has been clear that Democrats have a red-state problem in the Senate midterm elections: Seven Democratic seats are up for grabs in states Mitt Romney carried in 2012, three of them opened by retirements.

Republican Congressman Cory Gardner’s decision on March 1 to run against Democratic Sen. Mark Udall in Colorado—a state President Obama carried in 2008 and 2012—indicates that Democrats have a blue-state problem too.

The problem stems from President Obama’s poor approval rating, compounded by able Republican candidates like Mr. Gardner, a rising star in the House. …

… Sen. Udall is not the only Democratic incumbent so situated. If former Massachusetts Sen. Scott Brown challenges New Hampshire Sen. Jeanne Shaheen, she will have to contend with Mr. Obama’s low (44.6%) approval rating in the Granite State.

Sens. Tom Udall (N.M.), Jeff Merkley (Ore.), and Mark Warner (Va.) also face headwinds. Mr. Obama’s 2013 approval rating in each of their states was below his national average last year—45%, 45.4% and 46.4%, respectively. …

… In the six blue states with Democratic senators up this fall, Mr. Obama’s approval rating last year was below his 2013 national average in four and in two it was just above it. If the president’s ratings in these states have moved in tandem with his national number, he’s less popular in them now, since the president’s Gallup approval was down to 42% on Wednesday. History says it will be hard for Democrats to run much ahead of the president’s October approval number—and odds are that number will be lower than it is now.