WASHINGTON, D.C. - In defiance of President Donald Trump, who has taken a barrage of criticism from Republicans and Democrats for standing by Saudi Crown Prince Mohammad bin Salman after the murder of Jamal Khashoggi, the U.S. Senate issued a stunning bipartisan rebuke to Saudi Arabia's government and royal family Thursday, for the Washington Post journalist's murder, and for the escalating humanitarian crisis in Yemen, with a 56-to-41 vote to end U.S. involvement in Saudi Arabia's war against the Houthis there.

The 56 Yea votes in the Senate Chamber represent a broad, bipartisan coalition of Senators who are remarkably diverse in their political differences. The resolution was sponsored by Sen. Bernie Sanders (I-VT), the Senate Democratic Caucus's progressive champion, who is so far left in many respects that he is not even a Democrat, though he caucuses with them and ran for the DNC nomination for president in 2016.

Yet Sanders was joined in supporting the Yemen resolution by Sen. Mike Lee (R-UT), one of the most conservative members of the U.S. Senate. Sen. Kirsten Gillibrand (D-NY), a big government, New York liberal who may run for the Democratic Party's presidential nomination in 2020, also voted for the resolution, along with Sen. Rand Paul (R-KY), a Tea Party Republican from Kentucky, who ran for his party's presidential nomination in 2016.

Rand Paul has been one of the resolution's most outspoken supporters, keeping a hectic schedule of cable news interviews to tell audiences about the growing humanitarian crisis in Yemen, and put public pressure on the U.S. intelligence establishment for leaving Senators out of closed door briefings about the Saudi Kingdom, calling CIA Director Gina Haspel's exclusion of most Senators from these discussions "the very definition of the Deep State."

Parties and partisanship are nowhere to be seen amid these legislative foreign policy developments.

These matters are so complex that there is no easy reference guide for what the "Republican position" or "Democratic position" is on these issues. Rather than dividing along party lines and marching in lockstep, lawmakers are having to assess the situation and consult their own best instincts, knowledge, and governing principles to decide what position to take.

The U.S. House, which is more tightly controlled by the leadership of the party in power, is going to stall the resolution until the next session, so it won't be making it to Donald Trump's desk in the Oval Office this year, and even if it did, there hasn't been a veto-proof majority vote to keep Trump from rejecting it and standing by the U.S.-Saudi alliance against the Houthis in Yemen.

Still this Senate vote has been months, even years in the making, and represents substantial momentum in the direction of declaring U.S. neutrality in the war in Yemen, as well as a promising level of bipartisanship and policy-making on the basis of principles and real-world results, rather than putting on a show for the most rabidly partisan voters.

In Yemen the Saudi government has been waging a proxy war against Iran over mostly religious differences (Saudi Arabia is a Sunni Muslim theocracy, and Iran is the world's largest majority Shia Muslim nation). Saudi Arabia has been fighting to bolster the embattled government of Yemen's Sunni dictator, who was nearly overthrown by Houthi rebels in the aftermath of the Arab Spring.

The Houthis are a minority ethnic group consisting of a certain sect of Shia Muslims. The Houthi's rebellion against Yemen's central government in the 1990s met with failure, but after the Arab Spring, they went on the offensive again and captured the nation's capitol. They even began to win over broad popular support from Sunni Yemenis after doing more to stop Al Qaeda shootings and bombings in the country than the previous government.

U.S. military aid, including intelligence and logistical support such as mid-air refueling for Saudi bombers, has assisted Saudi Arabia in creating one of the worst humanitarian crises of the 21st century, with many Yemenis on the brink of starvation and a cholera epidemic worse than any the world has seen in modern times.