A White House official said that President Biden will announce sanctions on hundreds of members of Russia's lower house of parliament this week.
The announcement is expected to be made during a series of global summits in Europe on Thursday, when Mr. Biden will press Western leaders for even more aggressive economic actions against Russia.
The next phase of military assistance to Ukraine, new plans to expand and enforce economic sanctions, and an effort to further bolster NATO defenses along the border with Russia will be announced by Mr. Biden and other leaders in Brussels on Thursday.
Mr. Sullivan told reporters that the president was going to Europe to make sure that we stayed united, to send a powerful message that we were prepared and committed to this for as long as it took.
The president will wrap up the details of new sanctions and other steps during his deliberations in Brussels, officials said. Mr. Biden will face a steep challenge in confronting Mr. Putin's war.
The sanctions on Russian lawmakers will affect hundreds of them, according to the official who requested anonymity to discuss diplomatic deliberations that have not yet been publicly acknowledged.
The United States imposed financial sanctions on a group of people. A senior official said that the announcement on Thursday will go far beyond the sanctions. The details of the sanctions are still being worked out.
NATO has pushed the limits of economic sanctions imposed by European countries that are dependent on Russian energy. Most of the alliance's military options have been exhausted and it has not had a direct confrontation with Russia.
After three back-to-back, closed-door meetings, the president and his counterparts have a short list of announcements they can make on Thursday. Mr. Sullivan said there will be new targets for sanctions inside Russia. He said that the United States would make new announcements about helping European nations wean themselves off Russian energy.
The main goal of the summits, which have come together in just a week through diplomats in dozens of countries, may be a further public declaration that Mr. Putin's invasion will not lead to a war.
Mr. Sullivan said that the allies in Europe and elsewhere have remained more united than at any point in the past.
The violence in Ukraine has not been limited by unity. The United States and Europe have already imposed the broadest array of economic sanctions on a country of Russia's size and wealth, and there have been early signs that loopholes have blunted some of the bite.
Russia was able to make interest payments on its debt despite rumors that it might default. After plunging to record lows this month, the ruble has since rebounded.
The exception built into the sanctions allowed Russia to continue making payments in dollars through May 25. The loophole protects foreign investors and gives Russia more time to destroy Ukraine.
Russia has been able to rebuild its foreign reserves by selling energy to Europe and other places.
The chief economist at the Institute of International Finance said that Russia is generating a constant hard currency flow in euros and dollars because of the large trade and current account surplus.
The president is leaving Washington on Wednesday morning to attend summits with NATO, the Group of 7 nations and the European Council, a meeting of all 27 leaders of European Union countries. Mr. Biden will discuss the plight of the Ukrainian refugees in Poland on Friday. He will visit with American troops in Poland.
The president of Poland is expected to meet with the vice president on Saturday.
White House officials said new enforcement measures would be part of the announcements in Brussels.
Mr. Sullivan said that the announcement will focus on making sure that there is a joint effort to crack down on evasion on sanctions.
He added, "So stay tune for that."
Western allies could allow Russian energy exports to continue but insist that payments be held in an account until Mr. Putin stops the invasion, according to Sanctions experts. The United States used a similar method with Iran when it allowed some oil exports but required the revenue to be held in accounts that could only be used for bilateral trade.
Russia's force is decreasing. According to the Pentagon, Russia's combat power in Ukraine has fallen below 90 percent. The losses that Russian troops have suffered at the hands of Ukrainian soldiers are reflected in the assessment.
Cracking down on dissent. A Russian court sentenced the opposition leader to nine years in prison for fraud. The scope of government bodies off-limits to criticism has been amended by Russia.
Biden has a diplomatic push. President Biden will press allies for even more aggressive economic sanctions against Russia during a series of global summits in Europe this week, seeking to maintain unity of purpose as Russian forces continue to rain destruction on cities in Ukraine.
The United States and Europe could target Russia's major energy companies without banning oil and gas exports. American officials said that a move like that would hamper future energy exploration projects and cause long-term damage to its production capacity.
Biden administration officials have said they crafted the sanctions on Russia to allow for its energy exports to proceed, acknowledging Europe's reliance on Russian oil and gas and arguing that disrupting the market could have an adverse impact on the global economy.
In recent days, European leaders have come under increasing pressure from the U.S. administration as well as a core group of hard-liners within their ranks to impose an oil embargo on Russia.
Ahead of the meetings on Thursday, European Union leaders did not seem to be moving toward such a move, which would hit Germany the hardest.
European Union diplomats say that Germany is against an oil embargo because it would hurt European economies more than it would hurt Russia. Hungary has a huge dependency on Russian oil and is supporting Germany and Bulgaria. The Netherlands, which has sway in the bloc, is worried about the loss of revenue from its key port of Rotterdam if sanctions are imposed on Russia.
Russian coal is one of the major exports that has evaded European sanctions, and some E.U. countries are suggesting that the bloc take a closer look at the issue. The European Union should have largely abandoned coal as part of its green energy transition agenda, according to diplomats.
Mr. Biden's presence at the E.U. leaders summit could force more consensus among Europeans, but diplomats said a breakthrough on a Russian oil embargo was unlikely.
Mr. Biden came up with the idea of summits. He settled on it 10 days ago, aides and diplomats said, hoping to send a message to Russia and show the continued unity of the West.
Summits usually have months of preparation and end with a series of concrete actions that are agreed upon long in advance, and announced as if the leaders had debated them at the meeting and reached accord. There was not enough time to find accords on sanctions, long-term moves away from Russian energy and commitments of weapons for the Ukrainians.
A senior administration official said that the meeting was the symbol for Mr. Biden. He is gathering the nations of NATO to show their support. India and China have neither condemned nor endorsed Mr. Putin's actions.
Mr. Biden will have a chance to be among the refugees in Poland. At a time when Mr. Putin is bombing buildings and causing death from the skies as schools and arts centers and malls collapse, White House officials think that will be a powerful picture.
NATO will be the most critical of the meetings. There is a lot of concern about Mr. Putin's next move and what will happen if he uses chemical or biological weapons. There is no unity on how the West would respond to those possibilities so far, officials say, and Mr. Biden and his aides will have to take up the question behind closed doors.
Reporting was done by David E. Sanger, Matina Stevis-Gridneff, Alan Rappeport, and Zolan Kanno-Youngs.