THE MILT WOLF EFFECT: Roll Call: Where He Really Lives Aside, Sen. Pat Roberts Has Moved to His Right.

Sen. Pat Roberts might be in additional re-election trouble, thanks to a weekend story in The New York Times that’s generating buzz about how the Republican doesn’t have a home he can call his own in Kansas — but he does have a new case to make about his conservative credentials.

After 16 years in the Senate (and as many years before that in the House) cementing a reputation as an establishment Republican, one driven much less by ideology than by a desire for accomplishment, Roberts tacked hard to the right last year. In fact, among the six members of the Senate Republican Conference facing viable primary challenges, Roberts was unique in this regard: He opposed President Barack Obama much more often than before and also stuck with his party significantly more than he usually does.

The CQ Roll Call vote studies for 2013 found that Roberts voted against the president’s wishes 66 percent of the time, 6 points higher than the Senate GOP average. During Obama’s first term, the senator’s presidential opposition averaged 55 percent. . . .

Roberts is up against radiologist Milton Wolf, who’s counting on an energized tea party base to carry him to an upset in the Aug. 5 primary.

That’s likely one reason for what amounts to a seismic shift for a politician who had molded himself after two of his Senate forebears, Bob Dole and Nancy Landon Kassebaum. Roberts was in the top 10 among GOP senators voting against George W. Bush in the final two years of his presidency and once merited the backhanded compliment “not one of the impossible ideologues” from liberal former Rep. Barney Frank.

Ouch.