Vice President Biden arrived here Monday at a crossroads moment in Ukraine’s conflict with Russia, bringing U.S. economic assistance and warnings to Russian President Vladimir Putin that future intervention in the country’s volatile east will come at new costs.

Biden will meet here with Ukraine’s political leadership, civil society groups and U.S. diplomats over two days. He is the most senior administration official to visit Kiev since Ukraine’s crisis with Russia began two months ago, leading to Moscow’s annexation in March of Ukraine’s autonomous Crimea region.

A senior administration official, who spoke on condition of anonymity to discuss the trip in advance, said the vice president would announce a new U.S. support package to benefit Ukraine’s economy, energy sector and political reform efforts in the run-up to national elections next month.

The official said Biden will emphasize national unity as Ukraine heads into the May 25 vote, which may help settle a constitutional crisis over the presidency, as violence between pro-Russian groups and Ukraine’s security forces in the east remains a threat to the country’s “territorial integrity.” The visit comes just four days after Russian and Ukrainian officials agreed in Geneva to defuse the standoff in the east, although its viability remains uncertain on the ground.

“He will call for urgent implementation of the agreement reached in Geneva last week while also making clear, as we have done in recent weeks, the cost to Russia if it fails to de-escalate,” the official said. “There are currently ongoing threats to Ukraine’s sovereignty and territorial integrity, and the most effective response to that is for all of Ukraine to pull together.”

Biden in recent weeks has become the administration’s highest-ranking emissary to Eastern European governments worried suddenly over Putin’s ambitions in the region. Last month, he visited Poland and Lithuania, NATO member nations, where he reaffirmed the U.S. commitment to the pact’s essential collective security pledge.

In a visit to Europe late last month, President Obama also rallied European support for Ukraine and against Russia’s takeover of Crimea, which administration officials acknowledge will not likely return to Ukraine.

But the challenge presented by pro-Russian groups, which are now seizing government buildings and police stations in the eastern Donetsk region, remains, in the words of the official traveling with Biden, “the most acute” facing Ukraine’s leadership.

On Tuesday, Biden will discuss with Ukraine’s acting President Oleksandr Turchynov and Prime Minister Arseniy Yatsenyuk political reform efforts that seek to push more power to Ukraine’s regional governments. The official traveling with Biden said the vice president will also listen to additional military aid requests from Ukraine’s leaders, following the administration’s decision last week to send nonlethal assistance to Ukrainian security forces.

But the new U.S. support to be announced by Biden will focus on economic expertise, which will emerge from an assessment now being conducted by a U.S. team here on shifting Ukraine’s Russian-dependent energy supply toward one that relies more on domestic and Eastern European gas production.

The official said the U.S. energy consulting team will travel from here to Slovakia and Hungary to work on ways of reversing the flow of some of Ukraine’s pipelines now supplying Europe. Over the longer term, the official said, the U.S. government will work with Ukraine to help the government increase domestic gas production.

In addition, the official said, teams of U.S. economic advisers will arrive to assist Ukrainian officials in using $1 billion in recently approved U.S. loan guarantees and in securing a far larger assistance package from the International Monetary Fund.

Biden will also meet here with several dozen members of Ukraine’s parliament Tuesday representing regions from across the country. His message, the official said, will stress the need for unity ahead of next month’s elections to confront the enduring security threat and economic instability.

He will then speak with members of various civil society groups working to promote democracy and anti-corruption efforts, as well as those promoting youth and cultural programs.

On his arrival Monday, Biden headed through a city quiet with the Easter holiday to the U.S. Embassy, where he met with U.S. diplomats. Later, he will talk with a visiting congressional delegation for its assessment of the political and security situation before Tuesday’s official meetings.