US Republicans said Tuesday they will not write "a blank check" to war-torn Ukraine if they make the widely expected gains needed to take control of the House of Representatives in the midterm elections.

The warning from House minority leader Kevin McCarthy is the first official signal that Kyiv could be facing a tougher fight for funding as it fends off Russia's invasion, with bipartisan support beginning to wane in the United States.

"I think people are going to be sitting in a recession and they're not going to write a blank check to Ukraine. They just won't do it," McCarthy told online politics outlet Punchbowl News.

McCarthy hopes to become House speaker -- the third-most senior position in US politics behind the president and vice president -- if Republicans take over the House next year.

He said he expected voters to punish the Democrats in November's elections for neglecting domestic priorities such as a growing immigration crisis at the southern border.

"Ukraine is important, but at the same time it can't be the only thing they do and it can't be a blank check," McCarthy said.

The 57-year-old from California spoke out as Kyiv announced almost 1,200 towns and villages had been left without power after 10 days of Russian strikes that have destroyed one-third of the country's power stations, with winter approaching.

'Spending spree'

Since the start of Russia's expanded invasion in February, President Joe Biden's administration has allocated $17.6 billion in military aid to Ukraine -- although this is a fraction of the total bill including humanitarian assistance.

There has been cross-party support in Congress for the handouts, although a significant section of the Republicans' "America First" hard-right has objected.

Some analysts suggested that McCarthy's announcement was a concession to the party's right wing as he looks for votes to become speaker.

Others said his remarks may be aimed at juicing turnout among the traditionally isolationist support base of former president Donald Trump, with Republican strategists fearing many plan to stay home on Election Day.

"The Democrat spending spree never, ever ends. Biden needs to understand that we are the USA not the US-ATM," far right congresswoman Lauren Boebert tweeted last month.

All but a handful of House members voted against a $12.3 billion spending bill in September that included $3 billion for arms, supplies and salaries for Ukraine's military.

Democrats said McCarthy's interview demonstrated that Republicans could not be trusted with US foreign policy.

"Cutting off Ukraine in the middle of the biggest war in Europe since WWII indicates just how over his head McCarthy would be as Speaker," tweeted Ben Rhodes, a deputy national security advisor in Barack Obama's administration.

© Agence France-Presse