"Unfortunately so far he (President Barack Obama) seems to be strangely detached and Americans don't believe that he is leading" in a way that will cause the "defeat -- not stopping -- but the defeat of IS, who are a direct threat to the US," McCain said on Fox News, according to Xinhua.
The senator told Fox News last week that "We don't have to contain IS. We have to defeat IS."
"It's a debacle, and he (Obama) still doesn't get it," the senator said then, adding that the turmoil in Iraq was predictable after Obama's "huge mistake" of not leaving a small US force behind after pulling out of the embattled country in December 2011.
He called for a comprehensive strategy to defeat the IS using more than "pinprick airstrikes," saying "We're gonna need more boots on the ground -- and that does not mean combat troops -- but it does mean a significant increase."
Repeating calls Sunday for the administration to take the threat more seriously, he said: "The president has to lead. The president can change."
The hawkish senator was referring to what he sees as a commander-in-chief unfocused on the perceived terror threat and mirroring critics' consensus that the president is failing on foreign policy in general.
The Arizona senator has for weeks called on Obama to depart from what he has labeled the president's "failing" policy on the Islamic State.
The group has in recent months been on the march in Iraq and Syria, killing many victims in an orgy of violence after conquering a vast swath of territory in northern Iraq.
While Kurdish fighters and US airstrikes have had some success against the radicals in Iraq, they remain unchecked in Syria. The group beheaded US journalist James Foley and posted a video of the horrific action online last week, grabbing worldwide headlines.
McCain also called on the White House to be more transparent regarding plans to spend aid the administration has requested.
"No one has told us what it's going to be used for except for quote 'counter-terrorism,'" he said. "The president of the United States has to articulate the challenge, what we need to do to meet it, and describe exactly to Congress what those missions are."