WASHINGTON, Nov 25 - Two U.S. senators are pushing to boost shipments of lethal weapons to Kyiv as the West nervously watches Russian troops and equipment mass along Ukraine’s eastern border, Politico reported Thursday.

Sens. Rob Portman (R-Ohio) and Jeanne Shaheen (D-N.H.) are seeking to increase Pentagon funding to arm Ukraine by another $50 million as part of annual defense policy legislation being debated on the Senate floor.

But their effort, along with a heap of other proposals from senators in both parties, is in limbo after a push to secure votes on amendments to the National Defense Authorization Act hit a roadblock on the floor last week. And those measures could founder if senators don’t strike a deal when they return to finalize the defense bill after Thanksgiving.

The bipartisan package — which would boost the Pentagon’s security assistance to Ukraine to $350 million and wall off $125 million of that for lethal weapons — comes amid concerns on both sides of the Atlantic that Russia’s latest military buildup on Ukraine’s border could be different this time: a prelude to invasion.

Calls are getting louder from Capitol Hill for the Biden administration to act quickly to deter Russia, including by supplying Ukraine with more weapons.

In September, the Biden administration announced a new arms and military aid deal with Kyiv worth $60 million that included Javelin missiles and more intensive cooperation on cyber and research and development efforts. The pact increased U.S. military assistance for Kyiv to about $400 million in 2022, underscoring deepening unease in Washington over the grinding seven-year conflict.

Portman, who co-chairs the Senate Ukraine Caucus, called for a vote on his and Shaheen's measure. He also urged President Joe Biden to send more assistance on top of the new delivery of a pair of Coast Guard patrol boats.

"I urge the administration to provide further assistance in the form [of] anti-air and anti-armor capabilities which will be vital to deterring this latest Russian threat," Portman said in a statement Wednesday. "We must do all we can to stand with our ally Ukraine at this time."

Asked about the transfer of more lethal weapons, a senior administration official said the U.S. has “demonstrated that the United States is willing to use a number of tools to address harmful Russian actions and we will not hesitate from making use of those and other tools in the future.”

Ukrainian officials say about 92,000 Russian troops have taken up new positions near their borders, along with tanks, artillery and armed vehicles that could be used for a rapid offensive push.

The Biden administration has been warning European allies about Moscow’s intentions for weeks, sharing intelligence and huddling with military officials across the continent. Both the EU and NATO have also expressed concern over the new buildup. The Kremlin has pushed back, saying that the presence of NATO troops in Ukraine is a threat to Russian security.

The Defense Department originally requested $250 million for the Ukraine Security Assistance Initiative, the main Pentagon pot of money used to arm the country, in its fiscal 2022 budget.

Increased financial support to Ukraine has deep, bipartisan support on Capitol Hill. Competing defense policy bills in the House and the Senate already would boost the account to $300 million.

Portman and Shaheen want to green light even more assistance. Their amendment would boost the overall account to $350 million, a $100 million increase from Biden’s request. That money would go toward weapons, raising the minimum amount dedicated to lethal aid from $75 million to $125 million. (om/ez)