Updated at 12:25 p.m ET

Trump administration officials are expected to be grilled about Syria by angry lawmakers from both parties Tuesday afternoon.

The president's abrupt decision to order a withdrawal of troops in northern Syria has set off a flood of refugees from that country into neighboring Iraq. U.S. forces could also be observed withdrawing from Syria into Iraq on Monday.

A Turkey military operation targeting Kurdish forces began after President Trump announced he was withdrawing U.S. troops from northeast Syria. Trump's decision came after a phone call with the president of Turkey.

Supporters of the Kurds, an ethnic minority residing primarily in areas of Turkey, Iraq, Syria and Iran, believe that the U.S. withdrawal is a betrayal. One Syrian Kurdish leader warned that mass killings by Turkish forces could be next.

"We have always been promised by the United States, by U.S. officials that [we would] not be subjected to genocide. ... We only want them to keep their promises," Ilham Ahmed, a president of the Syrian Democratic Council, said through an interpreter during a news conference with U.S. lawmakers Monday evening. "Turkey is attacking us currently and we are subjected to ethnic cleansing."

It's in the context of this fast-moving development that James Jeffrey, the U.S. special representative for Syria, is scheduled to testify before members of the Senate Foreign Relations Committee Tuesday afternoon.

Some of the Senate's most vocal Republican Trump critics on this issue are on this committee, including Mitt Romney, who called Trump's withdrawal "a bloodstain on the annals of American history," and Lindsey Graham, who has departed from his usual role as a staunch Trump ally to criticize this decision.

On the other hand, the Senate panel also includes Rand Paul, who has been supportive of the president's move to withdraw troops.

Jeffrey will also testify Wednesday before the House Foreign Affairs Committee in a hearing titled "The Betrayal of our Syrian Kurdish Partners: How Will American Foreign Policy and Leadership Recover?"

Large numbers of Republicans and Democrats in both the House and the Senate have teamed up to rebuke the president's foreign policy decisions in Syria. Last week, the House voted on a symbolic resolution opposing the president's withdrawal decision. The vote was 354 to 60, with most Republicans joining Democrats in a rare show of unity.

The withdrawal has sent lawmakers scrambling to react. One of the few tools that members of Congress have with regard to foreign policy is the drafting and enactment of sanctions. Multiple groups of bipartisan lawmakers in the House and Senate are writing sanctions now to punish what they see as Turkey's bad behavior.

"This is an unusual issue in the sense it has brought the Congress together. ... There is wide and deep appreciation and bipartisan support for not abandoning [Kurdish military forces]," Graham said Monday evening.

Graham is currently working with Democratic Sen. Chris Van Hollen to pass a legislative package that would sanction the Turkish economy and impose penalties on the Turkish government's leadership.

Their proposal was moved directly to the Senate floor through a legislative procedure and could be brought up for a vote later this week.

"We're all in this together, pushing hard," Van Hollen told reporters Monday evening.

But that effort is effectively stalled because Senate Majority Leader Mitch McConnell, R-Ky., argued against immediate sanctions.

He cautioned in a floor speech Tuesday morning against "developing a reflex to use sanctions as our tool of first, last and only resort in implementing our foreign policy."

However, McConnell did say that he was planning to introduce a symbolic resolution urging Trump to rethink inviting President Recep Tayyip Erdogan to the White House and calling for an ongoing troop presence in Syria.

House lawmakers are also considering bringing up both a Turkey sanctions bill and a bill recognizing the Armenian genocide. Congress has previously debated whether to label what happened in 1915 — the period when roughly 1.5 million Armenians were killed — as "genocide." The Turkish government has historically strongly opposed this recognition and is expected to oppose both efforts.

"I'm sure the government of Turkey is not happy with [these plans], but then again we're not happy with the government of Turkey," said House Foreign Affairs Committee Chairman Eliot Engel, D-N.Y.

The United Nations has estimated that at least 160,000 civilians have been displaced by the fighting in northeastern Syria. Despite a tenuous and temporary cease-fire announced late last week — one that Turkish officials referred to as an operational "pause" — aid officials are preparing plans to host up to 50,000 refugees who may seek to cross the border from Syria into Iraq.

Copyright 2019 NPR. To see more, visit https://www.npr.org.