WASHINGTON House Democrats passed a nearly $1 trillion appropriations bill on Wednesday, complete with funding for the military, health programs and the Energy Department. But 11 lines in the 667-page bill could literally be the difference between war and peace, life and death: a repeal of the 2001 Authorization for Use of Military Force .

Three weeks after the 9/11 terrorist attacks, lawmakers overwhelmingly 420-1 in the House, 98-0 in the Senate approved the 2001 AUMF. The text of the resolution is incredibly broad. Congress gave the president the authority to use all necessary and appropriate force to go after the nations, organizations, or persons who were involved in the 9/11 terrorist attacks. But theres more.

The resolution also gave the president the authority to go after anyone who harbored those people, in order to prevent any future acts of international terrorism against the United States.

Not many lawmakers anticipated that, 18 years later, the United States would still be using the 2001 AUMF to justify military action all over the globe. Three different presidents have used the AUMF for more than three dozen different military engagements in 14 different countries.

And now, with President Donald Trump and his administration strongly signaling they would use the 2001 AUMF to justify a new war with Iran, the newish Democratic majority controlling the House is taking its most serious steps to repeal the war authority.

Included in the base text of the appropriations bill is a provision that would repeal the 2001 AUMF eight months after the legislation is enacted. It is a significant development in Congress trying to restrain Trump and many of his most hawkish advisers thirst for war. And its the first time the House has passed a repeal of the 2001 AUMF.

But this bill is almost certainly not the bill that will make it to Trumps desk. This is the first serve in an appropriations pingpong match between the Democratic House and the Republican Senate. Senate Majority Leader Mitch McConnell (R-Ky.) much less Trump is unlikely to accept such a repeal, and theres serious doubt among Democrats that their leadership would risk a shutdown over Senate Republicans refusing to repeal the 2001 war authority.

We are not the party of shutdowns, Rep. Jamie Raskin (D-Md.) told HuffPost this week. That is not our position.

If Democrats arent willing to risk a shutdown over repealing this 2001 military authorization, however, then theyre almost already giving up the game. They may have found a gambit that could potentially limit the presidents ability to go to war with Iran, but they face stiff opposition to a full-scale AUMF repeal not just from McConnell and Trump but also national security adviser John Bolton and Secretary of State Mike Pompeo. And even if they do plan to give up on repealing the 2001 war authority, they could still face stiff opposition in pursuing a middle-of-the-road approach.

The Trump administration is serious about a potential war with Iran. Bolton even said Monday that Congress would be making a big mistake if they doubted the presidents resolve on this.

A Generational Divide On War?

Much has been made of the generational divide among House Democrats. The top three leaders are in their late 70s and have collectively been in Congress for 94 years, while many of the newest Democratic members are three generations younger and still setting up district offices.

That means some of the newest members of Congress grew up with the Iraq War in the background of their high school and college years. Many of them opposed the invasion and saw politicians many of whom are now colleagues send their friends off to war. Despite the situation, Democrats swear there is no division.

I think Democrats are pretty united, Rep. Barbara Lee (D-Calif.) told HuffPost last week.

Remember the 420-1 vote in the House to approve the 2001 AUMF? Lee was the one member who voted no.

She has led the fight from the very beginning to repeal the authorization, and Lee genuinely believes Democrats of all ages and all congressional tenures are with her. We have to remember, Lee said, I believe its only 20% of Congress serving today served in 2001.