CANBERRA (Reuters) - Australia's Prime Minister Julia Gillard faces a leadership challenge after rivals called for a ballot to resolve months of slipping polls and internal tensions that put her minority Labor government on course to be swept away at September elections.

"This is not personal. It's about the party, the future of the country," said senior Labor minister Simon Crean, calling the challenge to break a deadlock between Gillard and chief rival Kevin Rudd, who she deposed in 2010.

Crean said Gillard had told him she would not call a leadership vote and he urged the Labor party to now pressure her to stage a ballot.

(Reporting by James Grubel; Editing by Michael Perry)