That approach is at odds with the one favored by the White House, congressional Democrats and many mainstream Republicans who believe that the best way to ensure funding for both wars is to keep them together in one large package. The $105 billion measure Mr. Biden has requested includes $14.3 billion for Israel and $61.4 billion for Ukraine, as well as funds for Taiwan and border security in the United States.
“At the end of the day, these are all going to be linked together, and we’re going to be voting on a package,” said Representative Michael McCaul, Republican of Texas and the chairman of the Foreign Affairs Committee, who has been working to persuade Mr. Johnson to embrace such a measure.
But Mr. McCaul conceded that, given the pressures inside his own party, Mr. Johnson could act as soon as next week to push through an emergency spending bill covering only Israel.
Since the start of the war, Mr. Johnson has routinely offered praise and prayers for Ukraine’s fight against Russia, but he has voted against successive emergency spending measures. Scores of House Republicans have adopted a similar stance, and last month, a majority of them, including Mr. Johnson, voted against a bill to send Ukraine $300 million to arm and train its fighters.
Mr. McCaul, Representative Michael R. Turner, Republican of Ohio and the chairman of the Intelligence Committee, and other top national-security-minded Republicans have been trying to impress upon Mr. Johnson that his new post requires a different approach to foreign policy than he has taken to date. During a Thursday meeting in the Situation Room with their Democratic counterparts and Jake Sullivan, the national security adviser, they stressed to Mr. Johnson that if he moved ahead with an Israel-only funding bill, he must offer Ukraine some assurances that its plight against Russia would not be forgotten.
“This is not something we want to play politics with; it’s a very urgent national security issue,” Mr. McCaul said after the meeting. “I think pulling out of Ukraine would be a terrible mistake.”
Mr. Johnson’s comments to Mr. Hannity suggested he had taken the warning to heart. He promised not to abandon Ukraine, and noted that allowing Russia to win would embolden other U.S. adversaries. But he has yet to specify when he might bring up an aid package for Ukraine, how large it might be or what restrictions would have to be included.
Senator Chuck Schumer, Democrat of New York and the majority leader, has pledged that his chamber will produce legislation to address multiple global threats, including Ukraine and Israel. Senator Mitch McConnell, Republican of Kentucky and the minority leader, has also stressed the urgency of addressing multiple crises at once, arguing in several floor speeches and a rare television interview that Congress must approve assistance for both Israel and Ukraine in order to counter Russia, Iran and China.
But bands of both House and Senate Republicans have been trying to stop that from happening.
On Thursday, five Republicans led by Representative Michael Waltz of Florida, a former Green Beret, wrote to Senate leaders warning them against including Ukraine funding in an aid package for Israel and the southern border.
“We are concerned that President Biden has used Israel’s existential struggle as an excuse to force billions more in additional spending through Congress, rather than address the nation’s most pressing emergencies,” they wrote.
A separate group in the Senate led by Senators Roger Marshall of Kansas and J.D. Vance of Ohio introduced legislation Thursday to provide military aid to Israel alone.
“Israel has an achievable objective,” Mr. Vance wrote in a memo he circulated among Senate Republicans before introducing the bill. “Ukraine does not.”