Despite the political buzz in Washington over the possible impeachment of US President Donald Trump, a story that dominates the headlines, attention to the Yemen war has not fallen off the radar screen of the US Congress.

That is because several influential members of Congress have attached or are signalling they will support an amendment on the Yemen war to the fiscal year 2020 National Defence Authorisation Act.

This act covers everything from military procurement and base construction to pay and health-care benefits. Because it is considered a bill vital to the national security of the country, critics of US involvement in the Yemen war see it as the best vehicle to attach amendments that would prohibit an American role in the conflict.

Earlier this year, a bipartisan group in Congress passed legislation that would invoke the War Powers Resolution concerning the Yemen war. That move would, in effect, end US military support for the Saudi-led effort against the Iran-backed Houthi rebels out of concern that the conflict has led to a grave humanitarian disaster and a heavy toll on civilians.

Given the partisanship prevalent in Congress, that vote was indeed historic, even more so because it was the first time the War Powers Resolution, which came into being in the waning years of the Vietnam War, was invoked by Congress.

Although Trump vetoed the legislation, with Congress not having the necessary two-thirds votes to override his veto, it sent a signal to the White House that there is strong opposition to US assistance to the Saudi-led campaign.

Not giving up, several US House of Representative members attached an amendment (passing on a 240-185 vote) to the House version of the defence act passed last summer that “prohibits support to and participation in the Saudi-led coalition’s military operations against the Houthis in Yemen.”

Although such language is not in the US Senate version of the defence act that also passed in the summer, several influential senators, including Bernie Sanders of Vermont, an independent seeking the Democratic Party nomination for president, and Mike Lee, a Republican from Utah, are in favour of the House language on Yemen.

They and other senators wrote a letter to their colleagues stating that the inclusion of the Yemen amendment in the final bill would ensure that US service personnel “are not involved in a war which has never been authorised by Congress and continues to undermine rather than advance US national security interests.”

The House and Senate bills are headed for conference, meaning that select members from each body go into closed-door negotiations to iron out differences and come up with a compromise bill that can be passed by both chambers. However, the champions of the Yemen provision are adamant about not giving in to their opponents.

Representative Ro Khanna, a Democrat from California and an outspoken critic of the Yemen war, said the Yemen provision is a “red line for House Democrats… The Republicans are going to push back and we are going to hold firm.”

The Yemen issue is not the only difference between the House and Senate versions of the defence act and it remains to be seen whether the House Democratic leaders are willing to fall on their sword to keep the Yemen language in the compromise bill. Undoubtedly, the leadership is weighing the political costs, such as whether Trump will use drawn-out negotiations and “intransigence” by Democrats to paint them as “not caring about the defence of the United States” going into an election year.

Peace groups and humanitarian associations are lobbying members of Congress not to drop the House version on ending US military involvement in the Yemen war. They are hoping that the coalition that came together this year to support the War Powers Resolution will re-emerge on the defence act but the outcome is uncertain.

The Trump administration, perhaps because of opposition in Congress, has been engaged in negotiations with the Houthis since at least early September to end the Yemen war, the Wall Street Journal reported. US Assistant Secretary of State David Schenker said the United States has been talking “to the extent possible with the Houthis to try to find a mutually acceptable negotiated solution to the conflict.”

The US negotiating team is reportedly led by US Ambassador to Yemen Christopher Henzel. Whether the effort will succeed is also uncertain. The Houthis are reportedly divided on whether to seek a compromise solution as are the Saudis, who support Yemen’s internationally recognised government. Reportedly, Washington is using Oman as the venue for such talks, which was used during the Obama administration.

If a breakthrough does occur in the next few weeks, that would take the wind out of the sails of the effort to include the Yemen provision in the final version of the defence act. If it does not occur, then a bitter fight between proponents and opponents of the provision is likely.