The most senior retired military officer to back the presumed Democratic presidential nominee, Sen. Barack Obama, says the first-term U.S. senator will not give Sen. John McCain, a decorated war hero, a pass on the issue of national security in the fall campaign.

“It doesn’t take very long to uncover national security issues that McCain is weak on,” retired Air Force Gen. Merrill McPeak told The Washington Times.

“For McCain to think he has a monopoly on virtue in the national security issue is going to be shown a pretty flimsy idea very quickly,” he said of the probable Republican nominee.

A Rasmussen poll released Friday showed voters giving Mr. McCain of Arizona a big edge over Mr. Obama on the question of who would make the best commander in chief.

“When it comes to the war in Iraq, McCain is trusted more by 49 percent of voters,” the Rasmussen Report said. “Obama is preferred by 37 percent. McCain has an even larger edge – 53 percent to 31 percent – on the broader topic of National Security. These results are little changed from a month ago.”

McCain strategists think their candidate’s steadfast backing for the war in Iraq will produce dividends on Election Day now that the troop surge appears to be defeating al Qaeda and bolstering the new democratic government in Baghdad.