Congress's top Democrat, Tom Daschle, lost his bid to be re-elected to the Senate, US networks reported Wednesday, capping a night of defeats for his party, which also failed to win control of either chamber of the US legislature.

Daschle, arguably the most powerful Democrat in the US Congress, lost the Senate's most closely-watched election in a 51 percent to 49 percent squeaker to Republican challenger John Thune, a former member of the House of Representatives.

In failing to hold on to the seat he first won in 1986, Daschle becomes the first Senate leader to lose re-election in more than half a century. Daschle was seeking his fourth term in the Senate.

Two years ago, Thune narrowly lost his challenge to the state's other Democratic senator, Tim Johnson.

Daschle faced tough race

Although a long-time South Dakota incumbent and the state's top politician, Daschle faced a tough race as a Democrat in an overwhelmingly Republican state.

GOP leaders in the US Senate made beating Daschle a priority and tapped the telegenic Thune, a former basketball star from the hamlet of Murdo, as their standard bearer.

Daschle won his last Senate race in 1998 race with 62 percent of the vote, but he was seen as more vulnerable after his flirtation with a presidential run this year alienated voters in his state.

Thune also succeeded in portraying him as a Washington DC liberal more likely to espouse a far left wing agenda in the Senate than the traditional bedrock heartland values that South Dakotans cherish.

Daschle and Thune spent more than $40-million in what has become the Senate's most expensive and bitterly-contested race.