WASHINGTON — President Barack Obama endorsed controversial bans on assault weapons and high-capacity ammunition magazines Monday, as well as stricter background checks for gun buyers — but conceded he may not win approval of all in a Congress reluctant to tighten restrictions.

“Will all of them get through this Congress? I don’t know,” said Obama. He said lawmakers would have to “examine their own conscience” as they tackle gun control legislation after the horrifying Connecticut school shootings and in the face of opposition from the National Rifle Association and other pro-gun groups.

Obama spoke at a midday White House news conference one month after the Newtown elementary school rampage, which ignited a national discussion on preventing mass shootings.

The president said he would unveil a comprehensive roadmap for curbing gun violence within days. His plan will be based on recommendations from Vice President Joe Biden’s gun task force, and is expected to include both legislative proposals and steps Obama can implement by himself using his presidential powers.

But the most sweeping and contentious elements — including an assault weapons ban — will require approval from a Congress that has been loath to tackle gun control legislation for more than a decade. The NRA has vowed to fight any measure that would limit access to guns and ammunition.

Despite the opposition, Obama said he would “vigorously pursue” measures to tighten gun laws.

“My starting point is not to worry about the politics,” he said.

The president’s new resolve follows a lack of movement in tackling gun violence throughout much of his first term, despite several high-profile shootings. He called the Dec. 14 massacre of 20 children and six adults at Sandy Hook Elementary School the worst day of his presidency, and vowed to take action.

White House officials believe moving swiftly on gun proposals at a national level, before the shock over the Newtown shooting fades, gives Obama the best chance to get his proposals through Congress.

Seeking to keep up the pressure on lawmakers, Obama said Monday that if “everybody across party lines was as deeply moved and saddened as I was by what happened in Newtown, then we’re going to have to vote based on what we think is best.”

Officials said Obama and Biden met Monday afternoon to discuss the vice president’s recommendations.

The president, without mentioning the NRA, said some gun rights groups have “a pretty effective way of ginning up fear on the part of gun owners that somehow the federal government’s about to take all your guns away,”

Seeking to ease those fears, Obama insisted that responsible gun owners who have weapons for protection or hunting “don’t have anything to worry about” under the proposals he will push.

The assault weapons ban, which Obama has long supported, is expected to face the toughest road on Capitol Hill. Congress passed a 10-year ban on the high-grade military-style weapons in 1994, but supporters didn’t have the votes to renew it in 2004.

Senate Majority Leader Harry Reid, D-Nev., on Friday predicted that a ban might win Senate approval but he doubted it could pass in the Republican-led House.