Russia has barred a second senator from entering the country as Moscow denies visas for American lawmakers critical of President Vladimir Putin while President Trump backs him on the world stage.

“While I’ve been a tough critic of the Kremlin, I also believe it’s important to maintain dialogue especially during moments of tension,” Connecticut Democrat Chris Murphy, a member of the Senate Foreign Relations Committee, said Tuesday. “Unfortunately, the Russian government is further isolating their country by blocking our visit and several others in recent months.”

Murphy is the second senator this week to announce that Russia denied his visa for foreign travel. Wisconsin Republican Ron Johnson’s office revealed Monday that the Kremlin spiked his trip. Johnson chairs the Foreign Relations subcommittee for Europe, while Murphy is one of four Democrats on the panel. Johnson's office said the bipartisan delegation planned to speak with Russian government officials, civil society activists, and American businesspeople.

“The path Vladimir Putin has chosen for Russia is a tragedy of historic proportions. Instead of holding free and fair elections, respecting the rule of law, and integrating Russia’s economy with Western democracies, Putin has invaded Georgia, attempted to illegally annex Crimea, conducted war in eastern Ukraine where thousands have died, and supported a barbaric regime in Syria that has used chemical weapons on its own people in a war that has resulted in the deaths of hundreds of thousands,” Johnson said, calling the denial a "petty affront."

A third senator, Utah Republican Mike Lee, said his visa was not rejected and he intended to make the trip.

The travel restrictions come days after Trump’s public advocacy for Russia to be readmitted to the Group of Seven, an assembly of the world’s largest industrialized democracies. The country was booted out after Putin invaded Ukraine and annexed Crimea in 2014.

"I think it would be better to have Russia inside the tent than outside the tent,” Trump said Sunday in Biarritz, France, following the annual G-7 meeting. “I really think it’s good for the security of the world. It’s good for the economics of the world.”

Senate Democrats condemned Trump's statements, with the ranking members of the Foreign Relations, Armed Services, and Intelligence committees joining Minority Leader Chuck Schumer in voicing their opposition in a letter to the president.

“Putin was rightfully excluded from the then Group of 8 (G8) following Russia’s invasion and illegal annexation of Crimea,” they wrote. “Under no circumstances should President Putin be invited to participate in the G7 until the Russian government undertakes demonstrable actions to show its willingness to behave responsibly both domestically and abroad.”

That letter, signed by New York's Schumer, New Jersey's Bob Menendez, Rhode Island's Jack Reed, and Virginia's Mark Warner, underscores the standoff between Russia and American lawmakers, even as the administration extends an olive branch to the Kremlin.

Murphy acknowledged the value of dialogue with Russia without hesitating to needle Putin by invoking the outbreak of protests over the Russian government’s refusal to allow key opposition leaders to run for office in Moscow's September city elections.

“With the collapse of recent arms control agreements and significant domestic opposition to Vladimir Putin’s authoritarian rule, this is potentially a perilous moment for our two nations’ fragile relationship, and it’s a shame that Russia isn’t interested in dialogue,” he said.