Democratic members of the Ukrainian Congressional Caucus held a press conference at the Capitol today to discuss allegations that US president Donald Trump delayed the release of funds appropriated to Ukraine in an effort to convince its president, Volodymyr Zelensky, to do his bidding.

“This is a very serious moment,” Ohio Democrat Marcy Kaptur, caucus co-chair, said. “The president can’t make release of funds contingent on a favor. No matter what president Trump thinks, Congress has the power of the purse.”

Kaptur said that the only official explanation given for the nearly two-month lag in release of a $391 million allocation to Ukraine, intended to help the nation in the face of Russian aggression, was “interagency delay.” Now, however, she says the just-released notes of Trump’s phone conversation with Zelensky supports allegations that the American leader sought a personal favor—for Ukraine to investigate his political rival Joe Biden. She called for “full documentation” of the phone call and said Trump’s actions “offend the Constitution.”

The contents of that phone call is now the subject of an impeachment inquiry opened this week by the US House of Representatives.

Brendan Boyle of Pennsylvania called Trump’s request “criminal” and expressed disappointment with the president. But he pointed out that an important issue was being obscured in the discussion about his phone call with Zelensky. Trump’s acts represent a threat to national security, Boyle said, and the president ignored the important role Ukraine plays geopolitically. The Eastern European nation is fighting “a second war of independence” against Russia, Boyle explained. Without US support, he warned Eastern Europe’s borders will eventually be redrawn by Russia. That, Boyle argued, matters to the US.

Ukraine exists in an uncomfortable space. It is the geographic divide between the West and Russia. And, as such, the two have jostled over influence and control of Ukraine since its independence from the Soviet Union in 1991. As long as Ukraine stays within the sphere of influence of the West, Russia lacks a foothold in Europe.

Things got particularly messy beginning in 2014, when pro-democracy protests calling for Ukraine to align itself with Europe dislodged the Russian-backed and spectacularly corrupt former Ukrainian president, Viktor Yanukovych. Not long after, Russia annexed the Crimean Peninsula, formerly part of Ukraine. Russian-backed forces, meanwhile, began supporting Ukrainian separatists in an ongoing war for control of the eastern part of the country that has killed thousands. Ukraine has since relied on US funds to help its military fend them off. This conflict was the very subject of Zelensky’s speech today at the UN, where he pleaded for help from the international community.

Congressman Bill Prascell of New Jersey called Trump’s seeming attempt to release appropriated funds only if Ukraine complied with his personal request an “abuse of power the likes of which has not been seen in a long time. “We have two smoking guns in both our hands,” he said.

But Americans may not be as convinced as some of their representatives. As the caucus members spoke, one group of passersby expressed their support for Trump. Meanwhile, throughout the discussion, an elderly onlooker muttered unhappily. When Kaptur explained that the caucus was signaling with the press conference that it stands with Ukraine, the displeased observer called out to Kaptur, “You should stand with Trump.”

The congresswoman, looking slightly surprised, replied, “We stand with the Constitution.”