As Russia continues to mass forces on its border with Ukraine, top Russian and U.S. diplomats are likely to meet this week in an effort to defuse the crisis.

Republicans and Democrats appeared increasingly united in their efforts to pressure Russian President Vladimir Putin to pull back his forces, with two key U.S. lawmakers saying Sunday they could soon have a deal on a package of sanctions meant to deter Russia from invading Ukraine and severely punish Moscow if it does.

This week may test whether efforts by the Biden administration and its allies to prevent a war in Europe are bearing fruit. Secretary of State Antony Blinken and Russian Foreign Minister Sergei Lavrov will probably speak again this week, a senior State Department official said, after earlier efforts by the top diplomats to reach a resolution were unsuccessful.

Victoria Nuland, undersecretary of state for political affairs, said Sunday that those talks would probably focus on written responses from the Biden administration to the Kremlin's demands for security guarantees. "We've heard some signs that the Russians are interested in engaging on that proposal," she told CBS News's "Face the Nation," pointing to the expected communication between Blinken and Lavrov.

"We want to settle these issues through diplomacy," Nuland said. Putin has "given himself that option, but he's also given himself the option of a major invasion. So we have to be ready for that."

President Joe Biden said Friday that he planned to send some U.S. troops to Eastern Europe to bolster NATO allies, describing the number as "not too many." The U.S. military has issued "prepare to deploy" orders to 8,500 personnel.

Senior U.S. lawmakers also said Sunday that they are optimistic about bipartisan agreement on issuing punishing sanctions against Russia.

"I believe that we will get there," Sen. Robert Menendez, D-N.J., chairman of the Foreign Relations Committee, told CNN's "State of the Union."

"We have been working in good faith," he said. "We've been accommodating different views and we are committed, jointly, in a bipartisan way to defend Ukraine and to send Putin the message: It'll be bluntly and consequential."

James Risch of Idaho, the committee's top Republican, said the two parties had hit a sticking point over the Nord Stream 2 pipeline, but he indicated that the differences were surmountable.

"We've had a disagreement on that, continuing disagreement, since the administration took office," Risch said. But he said that Germany's decision to halt certification of the pipeline, which could pump billions of cubic meters of Russian gas into Europe, had "changed the dynamics and open[ed] the door, really, for us to reach agreement."

The Biden administration will brief all senators in a classified setting on the crisis in Ukraine on Thursday, a Senate aide said.

Menendez said that some sanctions could be approved before a Russian invasion of Ukraine, a measure that Ukraine's ambassador to the United States, Oksana Markarova, said her government supports.

"We ask [for sanctions] both" before and after a Russian attack, Markarova told "Face the Nation." She said Russia had already invaded Ukraine in 2014, when it annexed Crimea. "And they didn't change their behavior during the eight years. So, yes, we believe the basis for sanctions is there."

Responding to U.S. concerns that Ukrainian President Volodymyr Zelensky was playing down the threat of an imminent Russian invasion, Markarova said leaders didn't want to panic Ukrainian citizens.

"We are not downplaying the risk. We actually see the situation the same way and we see the buildup," she said.

"To defend our country, we cannot afford to panic. We have to get ready, all of us, not only our military, our very capable military and veterans, but also all civilians. So we know and we see what is going on," Markarova added.

Britain's foreign secretary said Sunday that the United Kingdom would "widen" its sanctions on the Kremlin to include "companies involved in propping up the Russian state," as Washington and its allies intensified their efforts to deter a possible invasion.

The comments by Foreign Secretary Liz Truss came a day after Britain said it was preparing to send extra land, air and sea forces to Eastern Europe to support NATO allies.

Truss, asked about Putin's intentions during an interview with the BBC on Sunday, said it was "highly likely that he is looking" to invade Ukraine. "That is why we are doing all we can through deterrence and diplomacy to urge him to desist. That's why we are strengthening our sanctions regime here in the United Kingdom. We're going to be introducing new legislation so that we can hit targets including those who are key to the Kremlin's continuation and the continuation of the Russian regime."

In a separate interview with Sky News, Truss did not rule out the possibility that the sanctions could include seizures of property in London owned by Russian "oligarchs." She said "nothing is off the table."

The head of Russia's security council, Nikolai Patrushev, on Sunday dismissed U.S. warnings that Russia could attack Ukraine as "absolutely ridiculous" and said Russia did not want war.

British Prime Minister Boris Johnson said Saturday that deploying more British forces to the region, including jets, warships and military specialists, would "send a clear message to the Kremlin - we will not tolerate their destabilizing activity, and we will always stand with our NATO allies in the face Russian hostility."

Johnson is expected to speak to Putin this week and will visit the region in coming days.

Russia has repeatedly denied that its massive buildup of troops and military equipment around Ukraine, along with a wave of military exercises, is a precursor to a renewed assault.

"Today, they're saying that Russia is threatening Ukraine. This is absolutely ridiculous. There is no threat," Patrushev, the head of Russia's security council, said Sunday at a wreath-laying ceremony at a cemetery.

"We do not want war. We don't need it at all. Those who are pushing toward it, especially those from the West, they are pursuing some self-serving false goals of their own," he said, adding that war against Ukraine "does not suit us."

Russian officials are reviewing U.S. and NATO counterproposals on security, submitted last week in answer to Russia's earlier demands to limit NATO military activity in the former Soviet sphere.

Lavrov on Friday described the NATO response as "ideologically motivated" and "permeated with its exceptional role and special mission."

Western officials have warned that a Russian invasion, potentially one similar to its 2014 annexation of Crimea, could come at any time. U.S. intelligence, relying in part on satellite imagery, has found that Russia is massing forces around Ukraine in support of a potential incursion on multiple fronts.

Zelensky, Ukraine's president, said at a news conference Friday that the evidence of an imminent invasion was insufficient, accusing his Western counterparts of inciting "panic."

Asked Sunday about Zelensky's complaints, Linda Thomas-Greenfield, the U.S. envoy to the United Nations, said the Biden administration has been trying to ensure that Ukraine is "prepared" in the event of an attack.

"We've seen the Russian playbook before," she said. "They are using disinformation. They're encouraging Ukrainians not to worry about an attack. But we know that the attack is possible. You don't amass 100,000 troops if you don't have intentions to use them," she said during an appearance on ABC's "This Week."

A diplomatic resolution to the crisis would need to include "Russia making the decision to pull their troops back and to come to the diplomatic table and talk with the United States, with the Ukrainians, with our NATO allies, about their security concerns," Thomas-Greenfield said.

"We've made clear that we're prepared to address our concerns, Ukrainian concerns and Russian concerns," she said. "But it cannot be done on the battlefield."

Even the Ukrainian leader played down the threat of an invasion, though thousands of civilians across the country are training for the worst. Army reservists — some armed only with wooden replica weapons or those they've obtained on their own — receive basic combat training and in a time of war would be under direct command of the Ukrainian military.

Ukrainian citizens also have been trading advice about preparing for war on social media, including under the hashtag #миготові (#weareready).

The United States has requested a meeting of the United Nations Security Council on Monday to discuss Russia's military buildup, as it pushes for a diplomatic solution to the standoff. Moscow has described the meeting as a "PR stunt," but U.N. diplomats expressed confidence that any Russian bid to stop the meeting would be voted down, Reuters reported.

Biden is also set to meet Monday with Qatar's emir Sheikh Tamim Bin Hamad al-Thani as U.S. officials work to shore up alternative energy supplies for Europe, which relies on Russian natural gas exports, in the event that Moscow responds to potential sanctions by cutting off supplies.

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Amy Wang and Seung Min Kim in Washington contributed to this report.

previous coverage

• Biden says he plans to move US troops into Eastern Europe; Milley warns of ‘horrific’ casualties if Russia invades Ukraine