WASHINGTON (AP) — President Joe Biden is delivering an address to the nation Thursday night about the latest wave of mass shootings, attempting to increase pressure on Congress to pass stricter gun limits after such efforts failed following past outbreaks.

The speech follows last week's shootings by an 18-year-old gunman, who killed 19 students and two teachers at an elementary school in Uvalde, Texas, as well as one Wednesday in Tulsa, Oklahoma, where a gunman shot and killed four people and himself at a medical office.

And those came after the May 14 attack in Buffalo, New York, where a white 18-year-old wearing military gear and livestreaming with a helmet camera opened fire with a rifle at a supermarket in a predominantly Black neighborhood, killing 10 people and wounding three others in what authorities described as "racially motivated violent extremism."

The White House said Biden would speak at 7:30 EDT about the "tragic mass shootings, and a need for Congress to pass commonsense laws to combat the epidemic of gun violence that is taking lives every day."

Biden has used national speeches in the past to speak about the coronavirus pandemic and the chaotic withdrawal of U.S. forces from Afghanistan. But the president has used such addresses sparingly during his nearly 18 months in office, especially during evening hours

Earlier Thursday, Vice President Kamala Harris spoke about the Oklahoma shooting, saying, "All of us hold the people of Tulsa in our hearts, but we also reaffirm our commitment to passing commonsense gun safety laws."

"No more excuses. Thoughts and prayers are important, but not enough," Harris said. "We need Congress to act."

Before marking Memorial Day on Monday, Biden told reporters at the White House that there may be some bipartisan support to tighten restrictions on the kind of high-powered weapons used by the gunman in Uvalde. But he also noted that, while he had taken some steps via executive actions, he didn't have the power as president to "outlaw a weapon."

He also said that "things have gotten so bad that everybody's getting more rational, at least that's my hope," adding, "There's realization on the part of rational Republicans" who realize "we can't keep repeating ourselves."

Visiting Uvalde on Sunday, Biden mourned privately for three-plus hours with anguished families. Faced with chants of "do something" as he departed a church service, the president pledged: "We will."

His Thursday night address coincided with bipartisan talks that are intensifying among a core group of senators discussing modest gun policy changes. Republican Sen. Susan Collins of Maine said the group is "making rapid progress."

The private discussions in the Senate, which is split 50-50 between Democrats and Republicans, are not expected to produce the kinds of sweeping reforms being considered by the Democratic-led House — which has approved expansive background checks legislation and will next turn to an assault weapons ban.

Even a House package debated Thursday that is less sweeping, including a provision raising the required age for buying semi-automatic firearms to 21, faces slim chances in the Senate.

Instead, the bipartisan senators are likely to come up with a more incremental package that would federal funding to support state gun safety efforts, with incentives for bolstering school security and mental health resources. The package may also encourage "red-flag laws" to keep firearms away from those who would do harm.

No major gun legislation has passed the Senate in years — even after the devastating massacre of 20 children at Sandy Hook Elementary School in 2012.

The Senate did, however, approve a modest measure to encourage compliance with background checks after a church shooting in Texas and the Parkland school shooting in Florida.

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Associated Press Writer Lisa Mascaro contributed.