George Allen, the ambitious Republican junior senator for Virginia, is losing ground to his opponent in a key race that could help determine whether Democrats can seize control of the Senate in November’s congressional elections.

The latest Rasmussen poll shows Mr Allen’s lead over the Democrat Jim Webb has shrunk from 11 points a month ago to only five points; 47 per cent favoured Mr Allen with 42 per cent now preferring Mr Webb, a former marine and Reagan-era secretary of the navy, who is one of dozens of veterans seeking national office for the first time.