VILNIUS, Lithuania—Secretary of State John F. Kerry, on a trip originally scheduled to bolster European and Arab support for the Israeli-Palestinian peace process, arrived in this Baltic capital Friday with a second, more urgent goal.

In meetings here with European Union foreign ministers and with the Arab League in Paris Sunday, Kerry will seek more public and explicit condemnation of the government of Syrian President Bashar al-Assad for chemical weapons use and backing for a U.S.-led military action against him.

Administration attention is clearly focused most intensely on what is going on in the congressional debate over authorization for a military strike. Aides said Kerry would continue making calls to lawmakers over the weekend; he has already cut his trip short by two days to return to Washington on Monday.

But between the calls home, Kerry wants to talk to “some of our closest friends … about our latest thinking on Syria, how we see the situation developing in the coming days,” said a senior State Department official aboard Kerry’s plane.

“We also want to talk about where they can be helpful, especially in terms of building broader international consensus,” the official said, speaking on condition of anonymity prior to the discussions.

So far, the level of international support has been disappointing. Although the administration has said repeatedly that other governments agree with its assessment of the need to act on a red line against chemical use, relatively few have matched President Obama’s public determination..

Following the British parliament’s rejection of participation in a military attack, fewer still have said they would contribute resources to a strike.

Many U.S. friends have voiced concern about the lack of a United Nations mandate for the use of force, and said they would like to try again for a Security Council resolution, despite the fact that Russia and China continue to block a resolution.

In Paris, Kerry will also meet with French Foreign Minister Laurent Fabius, whose government has been the most outspoken in offering support, and possible participation, in a military strike against Syria.

For months before the Syria crisis exploded, Kerry spent much of his time and energy working on the Middle East peace process, eventually persuading the two sides to return to direct negotiations after a three-year hiatus. But since those negotiations began in July, he has had little opportunity to attend to the talks

A second State Department official rejected repeated reports that the talks are faltering, saying that not a single negotiating session has been cancelled, and statements indicating otherwise “are made by people who are ignorant about what’s going on.”

“Inevitably with so much turmoil roiling the Middle East…in some ways it’s a major distraction” to the peace process, the official said. But he also discerned a silver lining in the Syrian and Egyptian crises.

“For example, developments in Egypt, I think, have a fairly significant impact on the standing and credibility of Hamas,” whose Islamist rule in the Gaza Strip has lost a leading backer in the overthrow of Egypt’s Muslim Brotherhood government. As a result, the West Bank-based Palestinian Authority and President Mahmoud Abbas “is in a stronger position politically” to negotiate with Israel, the official said.

Kerry had hoped to meet with both Abbas and Israeli President Benjamin Netanyahu on his current trip. Instead, he will see Abbas on his last stop, in London on Monday morning, and return within the next few weeks to meet with Netanyahu.

While in Britain, Kerry will also meet with Foreign Secretary William Hague. The first State Department official went of his way to praise the British government, and Hague in particular, as a staunch U.S. ally despite last week’s Syria vote.

On other Syria-related matters, the official rejected reports that Obama has ordered the Pentagon to provide additional options for expanding what the administration has described as a “limited” attack on Syria.

While the Pentagon is reconfiguring target lists as Assad relocates assets, “these military operations, if undertaken, have a tightly, tightly defined purpose—to deter the [Assad] regime from again using chemical weapons…by making it harder for the regime to use them because it has fewer capabilities,” the official said. While “there are other programs and other efforts underway to change” the military balance on the ground in Syria’s ongoing civil war, he said, they “are not connected to this particular issue.”

The official declined to comment on specific U.S. weapons deliveries to the Syrian opposition ordered by Obama in June. The rebels , along with Sen. John McCain (R-Ariz.) following a recent visit to rebel-held areas inside Syria, have said the weapons have not arrived.

“The Syrian armed opposition is obviously receiving help from a variety of countries, including weapons,” the official said. “It wants a lot more than it’s getting and therefore it’s going to tell any visitor, including a distinguished American senator who is very sympathetic to their cause, that they want much, much more.”

“I do not discount their need,” he said, “but I recognize a certain negotiating tactic.”

After several months of reversals, the official said that the rebels have been gaining ground steadily against Assad’s forces.

Asked what a U.S. military strike would accomplish, the official said he did not “expect a huge, huge change on the ground on the day after. I think the war of attrition will grind on…without the use of chemical weapons, but it will grind on.”