Congress is poised to pass its first war-powers resolution ordering an end to U.S. involvement in hostilities overseas, rebuking President Trump’s embrace of Saudi Arabia and handing Democrats what they consider a vital component of their strategy for challenging him in 2020.

Trump’s strained relations with traditional allies in Europe, his warm words for Russia and his unpredictable approach to the Middle East have triggered broad bipartisan efforts to blunt his actions. But Democrats and Republicans remain mostly divided over restraining U.S. military support for the Saudi-led bombing campaign in Yemen, where a humanitarian crisis has raised questions about the moral and strategic costs of seeking lucrative weapons deals and enabling foreign wars, even as lawmakers appear set to send Trump their resolution.

Foreign policy is not traditionally a marquee campaign issue, nor is Congress usually the forum to forge presidential platforms. But with seven currently serving Democratic lawmakers hoping to replace Trump, such votes on Capitol Hill matter and could set the agenda for the party as a whole.

“National security is a huge opportunity for Democrats in 2020 because of how ham-handed President Trump has been in his relationships with the world,” said Sen. Chris Murphy (D-Conn.), who was among the earliest and most vocal agitators for a new approach to Saudi Arabia.

“If we don’t run a candidate who wants to talk about foreign policy,” he added, “we’re missing an opportunity.”

The United States has provided Saudi-led forces with logistical support and intelligence since 2015, aid aimed at beating back the rise of Iran-aligned Houthi rebels in Yemen’s civil war. Critics say the campaign has targeted civilians and choked off desperately needed humanitarian supplies, leaving more than 20 million Yemenis at risk of starvation.

Under pressure, the Trump administration announced late last year that it would stop refueling Saudi aircraft. But lawmakers in the House and the Senate have since secured votes on Yemen-focused resolutions to cease everything but intelligence sharing with the Saudis, a rebuke inspired in part by the killing of Saudi journalist and Washington Post contributor Jamal Khashoggi. Thus far, seven Republicans have supported those efforts in the Senate, and 18 in the House, along with the full roster of Democrats in both chambers.

It took a few years for these efforts to challenge U.S. activity in Yemen — a mission begun under the Obama administration — to move from a fringe issue in Democratic politics to one that party lawmakers fully support. Most Democrats made the shift in response to Trump’s early and unapologetic embrace of Saudi Arabia even as Yemen’s humanitarian crisis worsened. Khashoggi’s killing last fall, and Trump’s subsequent defense of Saudi Crown Prince Mohammed bin Salman despite intelligence assessments indicating he had ordered the slaying, fully solidified Democratic opposition to the Yemen venture.

The subject has been thornier for Republicans, who have condemned Saudi leaders over Khashoggi’s killing but wavered on whether to pull support for the military campaign as the president is expected to veto any congressional attempt to do so. Even those critical of the fight in Yemen have balked at endorsing a war-powers resolution because there are no U.S. ground troops there backing Saudi-led efforts against the Houthis — and because bipartisan efforts to limit arms sales to Saudi Arabia don’t have buy-in from party leaders.

As Republicans wrestle with the issue, Democrats have taken it to the campaign trail.

Within days of Khashoggi’s disappearance in Turkey last October, Sen. Bernie Sanders (I-Vt.), who wrote the Senate’s war-powers resolution, listed Yemen — along with Afghanistan and Iraq — as the United States’ most troubling military boondoggles. In a speech at Johns Hopkins’s School of Advanced International Studies, he declared that “Saudi Arabia is a country clearly inspired by Trump” and that it pursued the “catastrophic” war in Yemen, along with Khashoggi’s killing and other controversial ventures because its crown prince “feels emboldened by the Trump administration’s unquestioning support.”

The next month, Sen. Elizabeth Warren (D-Mass.) delivered a foreign policy speech at American University in which she said that Trump “refused to halt arms sales to Saudi Arabia in part because he is more interested in appeasing U.S. defense contractors than holding the Saudis accountable.”

“American security and American values should come ahead of the profit margins of these private companies,” she continued. “Foreign policy should not be run exclusively by the Pentagon.”

Though other congressional Democrats running for president have yet to make similar speeches outlining their foreign policy vision, they have — in tweets and in votes — expressed exasperation with and called for reexamining the alliance with Saudi Arabia.

Experienced Democratic strategists are urging party candidates to make Trump’s dealings with Riyadh a litmus test on the president’s character.

“It puts on display what so many Americans across the country really detest about the Trump administration: It’s rejection of American values, it’s putting the interest of an autocratic kingdom ahead of our own,” said Ned Price, a spokesman for National Security Action, a group of former Obama administration and Hillary Clinton campaign officials who have offered foreign policy advice to 2020 candidates.

Politically, Trump’s closeness to Saudi leaders is comparable to his praising Russian President Vladimir Putin, Price said, in that it’s “a question of what, precisely, is the motivation of people — including the president and his son-in-law” Jared Kushner, a senior adviser to the president, whose closeness with the Saudi crown prince has aroused suspicion among the administration’s critics, given reports that businesses tied to Kushner and his relatives have sought investment from Saudi Arabia and other Persian Gulf nations.

Democrats believe they can use the party’s stance on Yemen and Saudi Arabia to pitch a new foreign policy vision for the country — one that prioritizes diplomacy and economic engagement over a heavy reliance on the military and related industries.

Moving away from global military engagement has been a longtime rallying cry for far-left and far-right outside groups advocating for withdrawal from Yemen long before Sanders and Sen. Mike Lee (R-Utah) drafted the Senate’s version of the war-powers resolution.

Most congressional Democrats making presidential runs also embrace the idea of scaling back America’s global military engagement. Earlier this year, as some in the party warned that a Middle East policy bill admonishing Trump for seeking to abruptly withdraw troops from Syria and Afghanistan might be construed as an endorsement of “endless war,” only one Democrat running for the White House voted for it: Sen. Amy Klobuchar of Minnesota.

But even staunchly antiwar Democrats are aware that the party’s voters are not all as progressive on foreign policy matters as its current headliners or its activist base — and that simply being antiwar, when Trump is being excoriated for his proposed military drawdowns, is a losing strategy.

“Withdrawal can’t be what binds Democrats together heading into 2020,” said Murphy, one of the Senate’s most outspoken Democrats on military disengagement. “If all we are about is pulling out of Afghanistan, pulling out of Yemen, then we will not attract conservative Democrats,” many of whom have favored a hawkish approach to international affairs.

Democrats have not made a successful opposition foreign policy pitch since the Iraq War was at its height, when Barack Obama was running for president. With that in mind, Murphy has tried over the past few years to connect lawmakers with experts to study issues such as Saudi policy, and brainstorm new approaches to global threats. Several presidential hopefuls, including Sanders, Warren, and Sens. Cory Booker (D-N.J.) and Kamala D. Harris (D-Calif.), have participated in those discussions, according to people familiar with them.

Although most Democrats are still designing their foreign policy platforms, a few themes have emerged as candidates stump for prioritizing economic and humanitarian investment over weapons sales, diplomatic engagement over military deployments, and climate change as a means of rebalancing alliances with oil-rich nations such as Saudi Arabia.

“Democrats should be interventionists,” Murphy said. “I just think we should be proposing different tools for intervention than the U.S. Army.”