He’s got his commissioner’s back.

Mayor Bloomberg offered a spirited defense yesterday of embattled Transportation Commissioner Janette Sadik-Khan, two days after she withdrew a controversial proposal to plop down a pedestrian mall in the middle of 34th Street.

“This woman has made some real innovations here in this city that will last and will be a very big deal,” the mayor declared, speaking of the sweeping streetscape changes undertaken during his administration.

He argued that Sadik-Khan should be given credit for backing off the original 34th Street plan, saying that indicated she had listened to community concerns about closing the street to all traffic except buses and emergency vehicles between Fifth and Sixth avenues.

“That’s what she’s supposed to do,” said the mayor.

He chafed at a Post editorial that remained critical of his transportation chief.

“This woman can’t catch a break,” complained Bloomberg.