London ? Britain’s two main parties locked horns in a political standoff today after an inconclusive election — with Labour’s Gordon Brown signaling he would try to form a coalition and Conservative leader David Cameron declaring the prime minister had lost his mandate to govern.

Cameron — whose Conservatives strongly outpolled Labour but were projected to fall short of winning a majority of seats in Parliament — claimed that voters had rejected Labour in Britain’s election Thursday.

“Our country wants change. That change is going to require new leadership,” Cameron said early today, acknowledging negotiations may be needed to determine who will form the next government.

Speaking earlier in Scotland, Brown vowed to “play my part in Britain having a strong, stable” government — the clearest sign yet that he would try to cling to power and seek an alliance with the third-place Liberal Democrats. He also pledged action on election reform — a key demand of his would-be partners.