WASHINGTON — The Trump administration has struggled to find a way to counter Iran in Syria.

One strategy it has considered, according to analysts tracking the conflict and President Donald Trump’s statements, is to work with Russia to do it.

But new legislation being developed in Congress shows that US lawmakers are gearing up to resist the idea.

In the buildup to Trump’s summit last month with Russian President Vladimir Putin in Helsinki, debate within the US government on the idea of striking a deal with Russia on Syria spilled into the open. No deal was struck, said a National Security Council spokesperson. “During the two presidents’ discussions, there were no commitments to undertake any action, beyond agreement that both sides should continue discussions,” he said.

Yet Trump’s performance at the summit received scathing criticism across the political spectrum for appearing to defer to Putin on Russia’s meddling in US elections, Syria, and other issues. In the aftermath, concern among lawmakers about any potential deals with Russia spiked. “We need to be very clear with the president that we’re not doing some grand bargain with the Russians right now,” said a Republican congressional source who has worked closely on Iranian and Russian involvement in Syria. “There was a big push to do something pretty resonant and pretty expansive to send a message after Helsinki.”

The revolt has been bipartisan. Of a raft of new Russia-related bills and resolutions introduced in both houses since the July 16 Trump-Putin summit, the most sweeping is one cosponsored by Sens. Robert Menendez, the ranking Democrat on the Senate Foreign Relations Committee, and Lindsey Graham, a prominent Republican voice on foreign policy, along with four other senators.

Called the Defending American Security from Kremlin Aggression Act of 2018, the bill condemns Russia over a variety of issues, from its election meddling to its aggression in Ukraine, and it calls for a wide array of sanctions, including on political figures and oligarchs connected to Putin and on Russia’s energy projects and oil industry.

It also takes aim at Russia’s role in Syria — and at any agreement the US might make with Moscow as the conflict grinds toward an end.

The bill asks the US government to determine if Russia “meets the criteria for designation as a state sponsor of terrorism” — the same term US officials have applied often to Iran.

It seeks to tie Russia to Iranian forces and their proxies in Syria, requesting an assessment of whether Russia has provided weapons, technology, or military knowledge, either directly or indirectly, to Iran as well as to Syrian forces, the militant group Hezbollah, and other Iranian allies.

It spotlights the long-standing Russian policy of working in concert with the government of President Bashar al-Assad to strike medical facilities, aid convoys, and other civilian and humanitarian targets, seeking to know whether Russian forces have committed “war crimes and crimes against humanity.”

There is also an effort to underline a potential flashpoint between the US and Russia. In the section on war crimes, the bill includes a reference to “paramilitary forces or contractors responsive to the direction of [Russia].”

According to a congressional source who was involved with the bill, this language is meant to wrap in the Wagner Group, the shadowy Russian military contractor that has acted as an unofficial extension of Moscow’s military power in Ukraine, Syria, and other countries. The US Treasury Department sanctioned the group’s founder last year for its activities in Ukraine.

In February, Wagner’s mercenaries were reportedly involved in a four-hour attack against US forces by hundreds of pro-Assad fighters in eastern Syria. The attack was a “collective assault on US forces in which Wagner, Iran-aligned proxies, and Assad regime forces [acted] all at once,” the congressional source said, adding that it “suggests coordination, which means an arm of the Russian government actively participated in a direct assault on US forces.”

Finally, with a series of pointed questions, the bill requests the details of any deal President Trump may have stuck with Putin to limit Iranian influence in Syria.