President Barack Obama has briefed Congressional leaders on his plans for an expanded military campaign against Islamic State militants in Iraq and Syria.
He discussed his strategy with leaders from both parties at the White House.
The talks came ahead of a speech on Wednesday night in which he will make a case directly to the American people.
The White House described the meetings as “productive” and said Mr Obama had the authority to act against IS.
Tuesday’s meeting with Congressional leaders came a year after lawmakers blocked Mr Obama’s previous plans for missile strikes against Syria.
Since then, the IS jihadist group has taken control of large swathes of Iraq and Syria.
In June it declared the creation of a “caliphate” or Islamic state.
In the past month, IS militants have beheaded two US journalists in protest against American airstrikes on its forces in Iraq.
Mr Obama has ruled out the possibility of a US ground operation against IS but has signalled he may expand airstrikes to include Syria.
“Over the course of months, we are going to be able to not just blunt the momentum of [IS],” he said on Sunday. “We are going to systematically degrade their capabilities; we’re going to shrink the territory that they control; and, ultimately, we’re going to defeat them.”
At the White House on Tuesday, he met Democrats Senate Majority Leader Harry Reid and House Minority Leader Nancy Pelosi, and Republicans John Boehner, the speaker of the House of Representatives, and Mitch McConnell, the Senate minority leader.
“The president, vice-president and congressional leaders had a productive discussion and the leaders expressed their support for efforts to degrade and ultimately destroy [IS],” the White House said in a statement.
The White House said Mr Obama had told the congressional leaders he welcomed action from Congress in support of the effort and pledged “continuing extensive consultation”.
But Mr Obama’s aides suggested he would not seek new authorisation from Congress for military action.
“The president told the leaders that he has the authority he needs to take action against [IS] in accordance with the mission he will lay out in his address tomorrow night,” the White House said.
Mr Boehner, one of Mr Obama’s chief political adversaries, told the president he would back a US military deployment to train and advise the Iraqi security forces and assist in the targeting of IS leaders, an aide to the House speaker said in a statement to the BBC.
How do you fight Islamic State? Tara McKelvey, BBC News, Washington
Islamic State is cool – for aspiring jihadists. The group’s horrific videos of beheadings add to the Islamic State’s credibility, making their leaders seem more brutal than al-Qaeda.
“They’re the ones who are actually doing things,” says Humera Khan of Muflehun, an organisation that counters violent extremism.
In contrast, the US state department’s Welcome to the ‘Islamic State’ land, designed to demonise IS, is un-cool. Graphic and grim, its messages are ironic, written in state-department youth-speak: “Travel is inexpensive, because you won’t need a return ticket!”
It is part of a tradition of public-service campaigns designed to protect people from themselves. One 1960s film about drink driving, The Bottle and the Throttle, uses scary images and stern wording. It became a cult classic.
Like other well-intentioned films, Welcome to the ‘Islamic State’ Land comes across as preachy – and may not connect with its audience in the way its creators hoped.
According to a new Washington Post-ABC News poll, a large majority of the American public views Islamic State as a serious threat to the US and widely supports airstrikes in Iraq and Syria.
About 100 Americans are believed to have joined the militants and the US state department has tried to counter this by making a hard-hitting video that tries to dissuade potential recruits.
Meanwhile, France has announced it will host an international conference on Iraq on 15 September and President Francois Hollande will visit the country later this week.