Updated 11:56 a.m. | The Trump administration is taking a tepid line on an authorization for the use of military force, or AUMF, measure introduced Monday evening by Republican and Democratic senators, with a National Security Council official saying the president’s existing war powers are “sufficient.”

“Our position hasn’t changed,” the official said Tuesday. The 2001 AUMF, provisions in the U.S. Constitution and the force-authorization measure Congress passed and President George W. Bush made law before the 2003 Iraq war are “sufficient,” the NSC official added.

A second White House official said hours later the administration has yet to take an official position on the Senate’s new draft AUMF.

White House officials concluded late last summer they have ample legal authorities to continue conducting ongoing U.S. military operations such as Friday night’s missile strikes in Syria.

“The administration is not seeking a new AUMF, as the U.S. has sufficient legal authority to prosecute the campaign against the Taliban, al-Qaida, and associated forces, including against ISIS,” another NSC official said on Sept. 7.

Watch: Doing Nothing Is Doing Something — Trump, Congress and the Use of Force

White House officials have maintained that stance since, and issued no statements or tweets Monday night or Tuesday morning in favor of the AUMF rolled out Monday evening by Senate Foreign Relations Chairman Bob Corker of Tennessee and Democratic committee member Tim Kaine of Virginia.

[White House Provides No Internal Assessment Backing Mueller Firing Claim]

Administration officials were involved in efforts to craft the draft AUMF, Corker and Kaine said. The chairman last week labeled the White House’s role — with a grin — as “helpful.”

The senators’ much-anticipated and long-awaited draft authorization would repeal and replace the one passed a few days after the 9/11 terrorist attacks, and completely terminate the 2002 AUMF passed to authorize the Iraq conflict. It also would set new guidelines for the 17-year-old war on violent extremist groups like al-Qaeda, the Islamic State and others.

To the dissatisfaction of some Democratic senators, however, it would not slap restrictions on the kinds of military operations U.S. forces could conduct. That was a major sticking point in 2013, when efforts to craft an updated measure fell apart after members failed to agree on its specifics.

The Corker-Kaine measure does not include an expiration date, also to the chagrin of some senators. Such gripes make its passage out of committee uncertain.

Speaker Paul D. Ryan declined to say whether he would have the House take up the measure if it can pass the Senate but said he thought the president did the right thing by striking Syria last Friday.

The 2001 AUMF was written quickly and is legally vague, allowing three post-9/11 commanders in chief to use it as a legal rubber band, stretching it to cover all kinds of military missions against various groups in a list of countries where such groups didn’t operate in late 2001.

Whether President Donald Trump would veto the Corker-Kaine measure if it somehow reached his desk was left open by the NSC official.

The White House opposition comes despite Sen. Tim Kaine saying there were consultations with the White House throughout the process.

[Analysis: Trump’s Syria Strikes Highlight Congress’ War Powers Impotence]

Kaine said Monday night that he and Corker sought to address concerns raised by Secretary of Defense James Mattis about including an actual sunset for authorizations for using force against terrorist groups.

Watch: White House’s Sanders and Trump Imply Firing Authority Over Mueller

“They just felt like, if you do that, you’re sending a signal that you’re going to leave, and they’ll wait you out,” Kaine said of Mattis and others. “If it was just me, if it was just one vote, I’d put a sunset in, because I don’t think a sunset’s necessarily final. It’s just a review. But we came up with a middle ground.”

Like his fellow co-sponsors, Kaine said the authorization text is clear that it does not cover military action against sovereign countries.

“The thing that I’m probably the most happy about is this very clearly specifies that this is an authorization with respect to non-state terrorist groups. It does not provide any legal authority for action against a nation-state,” Kaine said.

Rachel Oswald and Lindsey McPherson contributed to this report.