Dick Smith to challenge Bishop if she runs

Entrepreneur Dick Smith has threatened to challenge Bronwyn Bishop in her seat of Mackellar at the next federal election unless the Liberal party chooses a younger candidate.

"It's much more likely if she is preselected that I will stand," Mr Smith told Fairfax Media on Friday.

"If they pick someone younger, I won't."

Senior Liberal Christopher Pyne said Mr Smith was entitled to run if he wanted.

But he was confident Mrs Bishop would be returned by voters if she chose to run.

"We give our members a real vote in pre-selections, we believe in democracy," he told the Nine Network on Friday.

"We don't believe in decisions being made in smoke-filled back rooms as they do in the Labor party factions."