The visit of the House speaker, Nancy Pelosi, to Kyiv at the head of a congressional delegation this week was a reminder that in Washington the Ukraine war is not just an issue of national security but is an increasingly important domestic political issue too.

In his approach to the conflict, Joe Biden, has the wind at his back in terms of US public opinion and Democratic party sentiment which is encouraging him to be ever more forward-leaning.

In a new poll conducted by the Washington Post and ABC News, 37% of Americans questioned said his administration was not doing enough to support the Ukrainians, fractionally more than the 36% who said he was doing the right amount. Only 14% suggested he was doing too much.

Late last month, the administration broadened US objectives in the conflict, to not just support Ukrainian sovereignty and territorial integrity but also to weaken Russia, with the aim of preventing a repeat of Moscow’s aggression against other countries.

A European diplomat suggested that one of the factors behind that shift was impatience in the higher levels of the party with the administration’s posture.

“It’s fundamentally about trying to get on the front foot in this crisis. There’s a lot of domestic criticism of the administration for being so passive,” the official said.

“The Hill [Congress] are cross and a lot of the big Democratic donors think it’s not being as forthright as America should be … Biden thinks he’s treading a careful path between intervention in its broader sense and keeping the focus on domestic concerns – and some Democrats are starting to think that balance isn’t right.”

Senator Chris Coons, a senior figure in Democratic foreign policy circles, has criticised Biden for taking direct military intervention off the table as an option. On the other side of the party, there has been little pushback from the progressive wing, which is normally sceptical about sending large quantities of military hardware into foreign conflicts.

And for once in Washington, the Republicans are pushing in the same direction.

“This is one of the few areas where Democrats and Republicans are reasonably well united and that makes it pretty easy for a president to move in that direction. He’s not making enemies,” said Larry Sabato, politics professor at the University of Virginia.

“The umbrella over all of this is the moral issue and the powerful video of Ukrainians being slaughtered and dislocated,” John Zogby, a pollster and political consultant, said. “Americans are moved by that and overwhelmingly support the Ukrainian people.”

It is nonetheless a political wedge issue. Support is more uniform among Democrats than Republicans. Donald Trump transferred his personal admiration for Vladimir Putin to at least some of his followers and the Fox News commentator Tucker Carlson, who has consistently raised pro-Moscow talking points on his show.

Democratic support is deepened by the important role of Ukrainian-Americans, thought to represent about 1 million people (Zogby thinks that is an underestimate) and who are influential on the party’s ethnic coordinating council. They have all the more sway because they are concentrated in swing states.

“You’ve got a decent number of Ukrainians in Ohio, and you have a Senate race in Ohio. There are Ukrainians in Pennsylvania and you have a Senate race in Pennsylvania,” said Wendy Schiller, political science professor at Brown University.

In Wisconsin, Democrats have been running ads against the incumbent Senator Ron Johnson, focusing on his 2018 visit to Moscow.

“It’s not an accident that Nancy Pelosi went to Ukraine,” Schiller said. “To have the speaker go, it says this is going to be an issue that the national party is going to take into the midterm elections.”

With state-level and national politics, moral outrage among the public and Biden’s own foreign policy instincts, all pointing in the same direction, the administration has sharply raised its stake in the Ukraine conflict, asking Congress for an extraordinary $33bn in military, economic and humanitarian support for Kyiv.

Public support, however, dies away dramatically when it comes to the question of sending US troops. Only 21% asked in this week’s poll backed such direct intervention, and concern about Ukraine escalating into a nuclear conflict is significantly higher among Democrats than Republicans.

Biden, who has made extricating the US from “forever wars” his signature foreign policy, has repeatedly said he will not send US troops into Ukraine, and has cancelled routine missile tests to reduce any risk of misunderstanding and miscalculation between the two nuclear superpowers.

“Boots on the ground may very well be a very different story,” Zogby said. “I don’t think world war three polls very well.”