WASHINGTON — President Obama on Tuesday will begin laying out his case for an expanded military campaign against the Islamic State in Iraq and Syria when he faces congressional leaders who are averse to taking an election-year stand but are being pushed by lawmakers who want a say in matters of war.

Mr. Obama’s meeting with Republican and Democratic leaders on Tuesday in the Oval Office will be the first of several between White House officials and lawmakers as the administration tries to persuade Congress to embrace the president’s plan to halt the momentum of the Sunni militant group known as ISIS.

A year after opposition in Congress thwarted plans for missile strikes in Syria, the White House is again putting the issue of military force in the Middle East before a skeptical Congress and a war-weary public.

Mr. Obama has not indicated yet whether he will seek congressional authorization, though he said Saturday he would like “buy-in” for a broader campaign, which the White House so far has not defined.