Israeli Prime Minister Benjamin Netanyahu said in broadcast remarks on Tuesday there was a "huge, worldwide effort" to ensure he loses next week's closely contested election.
Army Radio, which aired what it said were comments he made on Monday to activists of his right-wing Likud party, interpreted them as referring to foreign funding for advocacy groups campaigning for a change of government in Israel.
Political parties in Israel are banned from accepting money directly from overseas donors during an election campaign. But such funding is allowed under Israeli law for non-profit organisations espousing political viewpoints, and US consultants have advised Israeli candidates for years.
"It is a very tight race. Nothing is guaranteed because there is a huge, worldwide effort to topple the Likud government," said Netanyahu, who received rousing applause in the US Congress last week during a speech against a potential nuclear deal with Iran sought by the administration of President Barack Obama.
The visit came at the invitation of the Republican leadership of Congress, angering the White House and Democratic legislators. Critics accused Netanyahu of intervening in US politics, and the Republicans of trying to boost his re-election prospects.
Likud and the centre-left Zionist Union are running neck-and-neck in opinion polls ahead of the March 17 ballot, with Netanyahu widely seen by political commentators as having a better chance of forming a governing coalition after the vote.
As election day approaches, "Netanyahu is feeling the pressure ... he is shooting in all directions", Zionist Union leader Isaac Herzog told Israel Radio.