The Guardian yesterday ran up the white flag and called a halt to "Operation Clark County", the newspaper's ambitious scheme to recruit thousands of readers to persuade American voters in a swing state to kick out President George W Bush in next month's election.

The cancellation of the project came 24 hours after the first of some 14,000 letters from Guardian readers began arriving in Clark County. The missives led to widespread complaints about foreign interference in a US election.

It also prompted a surge of indignant local voters calling the county's Republican party offering to volunteer for Mr Bush.