WASHINGTON >> President Barack Obama will outline plans this week for an expanded U.S. campaign to defeat violent Islamic State militants in Iraq and Syria, a strategy that will also involve cooperation from allies in Europe, the Middle East and elsewhere.

Obama will launch an aggressive effort to build support for his strategy on Capitol Hill and with the American public. He’ll meet with congressional leaders from both parties at the White House Tuesday, then deliver a speech detailing his strategy on Wednesday.

The president’s address will come on the eve of the 13th anniversary of the Sept. 11, 2001 terror attacks. While U.S. officials say they do not believe the Islamic State currently has the capacity to carry out that type of attack, the Obama administration sees an urgent need to stop the militants from gaining that ability.

Officials say Obama’s strategy will include military, political and diplomatic efforts.

The U.S. is already launching airstrikes against Islamic State targets in Iraq and Obama has been considering expanding that effort into Syria, where the militants have a safe haven. The president is also pressing Iraq’s government to fulfill pledges to form a more inclusive government. And he wants Arab nations, particularly Sunni-majority states, to join the West in efforts to confront the Islamic State.

But Obama has ruled out putting U.S. military personnel on the ground in either Iraq or Syria in a combat role. Officials say he instead sees U.S. air power as a way to give cover to Iraqi forces and possibly Western-backed rebels in Syria and help them take on the militants.

"This is not going to be an announcement about U.S. ground troops," he said in a weekend interview with NBC’s "Meet The Press." He added that the operations will be "similar to the kinds of counterterrorism campaigns" the U.S. has waged in the past.

House Intelligence Committee Chairman Mike Rogers, R-Mich., welcomed Obama’s efforts to form an international coalition to join the U.S. in such efforts. He also said Obama needed to engage with lawmakers and the public.

"I think in Congress we need to expose all members to the level of threat that those of us on the national security committees see every day," Rogers said on MSNBC. He added that Washington political leaders should not give the Islamic militants the "time and space" to grow into a more formidable force, which he said happened with the al-Qaida terrorist network.

While Obama has promised to coordinate with Congress, he has not said definitively whether he will seek congressional authorization for any military action he will take. He did not seek authorization for lawmakers for the airstrikes the U.S. is currently launching inside Iraq.

The president did formally notify Congress Monday that the U.S. opened a new front in the airstrike campaign over the weekend, hitting targets around the Haditha Dam.

The airstrike campaign began before the Islamic State group announced that it had beheaded two American journalists in Syria. The murders of James Foley and Steven Sotloff sparked outrage in the U.S. and around the world and added new urgency to discussions over how to go after the militants.

In addition to laying claim to territory, the militants have targeted religious and ethnic minority groups and threatened U.S. personnel and interests in the region. And U.S. and European officials fear that an influx of foreign fighters who have joined the militants could ultimately return to their home countries and launch attacks there.

Obama sparked criticism, most of it from Republicans, for his remark last week that "we don’t have a strategy yet" for confronting the extremists.

His upcoming sessions with lawmakers and the speech to the nation are clearly an attempt to try to show he now has an evolving strategy in place.

"The next phase is now to start going on some offense," Obama said in the NBC interview.

Former Republican presidential candidate Mitt Romney suggested Obama has been indecisive in dealing with the crisis in Syria as well as other foreign-policy challenges.

"I think the president is really out of touch with reality when it comes to what’s happening in the world," Romney said on Fox News. "He is so out of touch with reality that he hasn’t taken the action necessary to prevent very bad things from happening."