WASHINGTON — If Congress declines to formally authorize US strikes against the Islamic State, one key senator predicts some members will try to end the military operations.

Sen. Tim Kaine, a Virginia Democrat who has introduced one of a handful of authorizations pending in both chambers, pressed hard during a Wednesday forum for Congress in coming months to debate and vote on a legal underpinning for President Barack Obama's air strikes on the violent Islamic group.

Obama last week announced he will ask Congress to approve the strikes. Due to a crowded lame duck session agenda, and the need to craft a force-authorization measure both chambers can accept, it appears Kaine's desired debate and vote will have to wait until the new Congress takes over next year.

Speaking at the Woodrow Wilson Center here, Kaine reiterated his months-long arguments for an Islamic State-specific measure or an updated version of the authorization for use of military force (AUMF) passed shortly after the 9/11 attacks, or both.

Among the Senate's most vocal proponents of authorizing the conflict, Kaine said doing so could be coupled with an effort to update the post-9/11 AUMF to reflect a changed al-Qaida and fights against new groups in new countries.

Kaine sees support for an authorization on both sides of the aisle, saying a debate would not be a replay of Washington's Obama-era partisan battles.

But, he warned, if Congress does not hand the commander in chief formal legal cover for the air strikes, some members could seek a different kind of action.

The Senate Foreign Relations Committee member bluntly said that shy of a debate and vote, some lawmakers "absolutely" will introduce measures designed "to get in the way" of the air strikes and ultimately "stop a war."

Kaine said committee leaders are talking with the White House about the language of an authorization measure, predicting the eventual resolution will be a "Frankenstein job." That means a measure that takes provisions from the handful of versions that have been introduced in the House and Senate, including one written by Kaine.