Prime Minister Stephen Harper would be "misguided" if he chose to call a federal election before Parliament resumes sitting on Sept. 15, NDP Leader Jack Layton said Thursday.

Layton was commenting in Montreal, where he's campaigning with candidate Anne Lagace-Dowson in advance of next month's byelection in Westmount-Ville Marie. Voters are set to go to the polls to fill vacancies in three ridings on Sept. 8 and in a fourth riding on Sept. 22.

Harper said earlier this week that Parliament was not functioning properly and that he would decide in the next few weeks whether to proceed with the fall session or call an election.

The NDP leader said Harper's assertion that Parliament isn't working is at odds with the facts.

"He's managed to get his entire program through with the help of the Liberals and the Bloc [Québécois]. So it's actually not a valid complaint," Layton said. "So he's up to something."

Harper is expected to meet with each of the opposition party leaders before Parliament resumes.

Layton said it's up to the prime minister to make Parliament work and he intends to ask him to work with the other parties to accomplish that.

"I'd love to see a prime minister who says lets all roll up our sleeves and work together," he said. "I'm not holding my breath, but that's what I'd like to see."

On Tuesday, Harper and Liberal Leader Stéphane Dion both talked to reporters about election timing, but neither would say they were ready to trigger a vote.