Hawkish Republicans have leaned on President Obama for the better part of a year to give weapons to Ukraine as it battles Russian-backed separatists. Now it’s members of Obama’s own party—both within Congress and from members of his own administration—that are calling on the president to arm the Ukrainians, before they lose even more territory to the Kremlin’s proxies.

On Capitol Hill there is a renewed sense of urgency: The top-ranking Democrat on the House Armed Services Committee, Adam Smith, will join with his Republican counterpart Mac Thornberry on Tuesday to present a bill that would further pressure the president to give the Ukrainian government weaponry, although legislators have yet to spell out the specifics of the bill.

And in the last week, a bevy of Democratic pols and former diplomats have said that the United States should do more.

“Later this week—if it goes any later than that...” Rep. Eliot Engel, the top-ranking Democrat on the House Foreign Affairs Committee, told The Daily Beast on Monday. “They need the weapons, they need them soon, and they need them quick. Our credibility is on the line, and what’s right is on the line,” Engel said.

Engel had just returned from the Munich Security Conference, where he had spoken with Ukrainian President Petro Poroshenko, who has said a better-armed Ukrainian army is the best means to discourage further Russian support of separatists.

“I’ll be satisfied when the president this week, hopefully, announces that we’re going to be giving the Ukrainians defensive armaments,” Engel said.

So far, the United States has said it would give $120 million in non-lethal military assistance to Ukraine. President Obama has the authority to pledge more: In December, lawmakers unanimously gave him the authority to spend $350 million over three years to provide so-called defensive weapons to the government of Ukraine. Those could include anti-tank weapons, ammunition, and radars that can detect incoming artillery projectiles.

“The feedback we are getting is [lethal defensive aid] is really a bipartisan issue,” said Pavel Yarmolenko, a spokesman for the Ukraine Freedom Support Group, an organization dedicated to pressing Congress to aid Ukraine. “It seems that people really understand that unless there is pushback against aggression by Russia, this could undermine not just Ukrainian sovereignty but also NATO.”

Last Thursday, more than 30 House lawmakers wrote a letter urging the White House to swiftly increase military assistance. Signatories included Democratic heavyweights like Engel, Smith, Minority Whip Steny Hoyer, and Ukrainian Caucus co-chairs Reps. Marcy Kaptur and Sander Levin.

That same day, Democratic Sens. Harry Reed, Richard Blumenthal, Joe Donnelly, and Bill Nelson joined with Republican hawks to warn against the Russian threat to Ukraine.

“Ukrainians are being slaughtered and we have a role to play in imposing restraint… We need to see that [Russian President Vladimir] Putin understands nothing but force. He is a thug, he has not responded to sanctions,” Blumenthal said.

Nelson added, “We simply cannot let Vladimir Putin get away with invading another sovereign country.”

Although Engel and others expect a decision in their favor this week, at the Pentagon, officials who once believed such aid was inevitable now seem more dubious.

“I don’t think [Obama] will do it,” one Pentagon official told The Daily Beast on the condition of anonymity so he could speak candidly.

In the last week, Germany and France have led an aggressive push for a renewed ceasefire effort. German Chancellor Angela Merkel and French President François Hollande have met with and spoken to Putin pushing for a ceasefire, saying they adamantly oppose sending more weapons.

Should the administration provide lethal aid, it would mark a major break with these allies, who believe the world community should give sanctions more time to pressure the Russians to step back. Some also fear more weapons would prolong the conflict.

In a joint press conference with Merkel on Monday at the White House, the president said providing lethal defensive aid was one of several options. But the president also emphasized that he was going to allow diplomatic efforts to play out this week and sought to disavow Russia of the perception that the United States and Europe were divided about how to respond.

“The possibility of lethal defensive weapons is one of those options that’s being examined. But I have not made a decision about that yet,” Obama said. “If, in fact, diplomacy fails this week, there’s going to continue to be a strong, unified response between the United States and Europe.”

Political leaders from France, Germany, Russia, and Ukraine have agreed to meet Wednesday in Minsk. Merkel has thus far been downcast that those talks will lead to a ceasefire. Either way, the prospect appears to have bought more time for the administration to make a decision.

In the past two weeks, violence has escalated in Ukraine. Last month, dozens were killed when Russian-backed separatists fired Grad rockets far beyond agreed-upon ceasefire lines.

Separatists have gained approximately 500 square miles and an airport in Donetsk since September, when both sides signed in Minsk an earlier agreement, which was supposed to lead to a ceasefire. At least 5,300 have been killed and an additional 1.5 million citizens have been displaced since April.

“It is appalling that Russia is sending in very modern equipment and using rocket-propelled systems, while Ukrainians have no way to defend themselves, and I don’t think that you leave a nation like that undefended,” Democratic Rep. Marcy Kaptur told The Daily Beast.

“They really were left in the lurch for a very long time, and I mourn the deaths of thousands of people who died because they simply weren’t ready. It’s like David and Goliath,” Kaptur said.

Democratic hawkishness may seem surprising. But since at the least the 1990s, there’s been a growing wing of liberal interventionists who believe U.S. intervention is the best resource to stop a foe; the push to intercede in Kosovo was one early example. Such advocates, most notably presumed 2016 presidential Democratic nominee Hillary Clinton, have more recently pushed for U.S. intervention in Afghanistan, Libya, and Syria.

All the while, Obama has become more reticent to get America involved in conflicts that do not pose a direct threat to the United States, particularly after U.S and NATO intervention in the 2011 uprising in Libya, a nation now overwhelmed with jihadis from groups like the self-proclaimed Islamic State. Obama’s foreign-policy approach is shared by most Americans, according to several polls. The result is that many of Obama biggest critics on Ukraine reside within his own party—sometimes within his coterie of advisers.

Ashton Carter, Obama’s defense secretary nominee, said he would be “inclined to” give the Ukrainian army more lethal aid during his confirmation hearing Wednesday. And NATO commander Air Force Gen. Philip Breedlove said last week that “I don’t think we should preclude out of hand the possibility of the military option.”

Secretary of State John Kerry was more vague about where the administration was leaning.

“I have no doubt that additional assistance of economic kind and other kinds will be going to Ukraine,” Kerry said in an interview Sunday on NBC’s Meet the Press. “We do so understanding that there is no military solution. The solution is a political, diplomatic one.”

Since Feb. 1, when The New York Times first reported that Obama was considering lethal defensive aid, former Cabinet secretaries, Pentagon leaders, generals, and ambassadors have lined up and urged the president to give the Ukrainian army more. Such aid could make Russian intervention too costly and push Russia to the negotiation table, they argue.

Former Secretary of State Madeleine Albright and former U.S. Ambassador to NATO Ivo Daalder urged the United States to do more for the Ukrainian allies. A group of scholars, including Michele Flournoy, Obama’s former undersecretary of defense for policy, also urged the president to do more, in a paper published by the Atlantic Council.

“There is a growing divide among Democrats who for a long time were positioned as very robust supporters of multilateral intervention. And on issue after issue, they have been by and large aligned with conservatives like John McCain. At the same time, I think there is a shift going on in the White House,” said Sean Kay, a professor in the department of politics and government at Ohio Wesleyan University, who wrote about the risks of potential U.S. intervention on behalf of the Ukrainian army.

Opponents note that weapons alone are unlikely to help the Ukrainian army against Russian-backed separatists. And if U.S-provided lethal defensive weapons fail to stop Russian intervention, America could find itself next providing offensive weapons like tanks, a slippery slope to a proxy war for something that Obama has said does pose a direct threat to the United States. Russia has denied it is providing weapons to separatists.

“What advocates of arming Ukraine fail to understand,” John J. Mearsheimer, a professor of political science at the University of Chicago, wrote in the Times on Monday, “is that Russian leaders believe their country’s core strategic interests are at stake in Ukraine; they are unlikely to give ground, even if it means absorbing huge costs.”