A new poll shows that NDP leadership hopeful Avi Lewis could buoy the party’s chances in a prospective federal byelection in Beaches-East York.

The Mainstreet Research survey has the NDP winning the support of 42.6 per cent of leaning and decided respondents in the Toronto riding, compared to 39.5 per cent for a generic Liberal candidate.

The Conservatives had 13.7 per cent of support, while the Greens were a distant fourth with 2 per cent, tied with the other party option.

The riding could open up in the near future after incumbent Liberal MP Nathaniel Erskine-Smith said he’s planning on leaving federal politics to run for the leadership of the Ontario Liberals.

Erskine-Smith said he’s running for the nomination of the provincial party in the yet-to-be called byelection in Scarborough Southwest, the riding former provincial New Democrat Doly Begum held until she resigned the seat earlier this year to run for the Liberals in the federal Scarborough Southwest byelection, set for April 13.

Erskine-Smith said he’d resign as an MP once Premier Doug Ford calls the provincial byelection.

Lewis is seen as the frontrunner in the NDP leadership race, which will wrap up later this month. His top challengers appear to be labour leader Rob Ashton and Edmonton MP Heather McPherson.

Mainstreet tested three potential ballot scenarios in Beaches–East York in a phone survey of 440 voters in the riding conducted between March 11-13. The firm says the margin of error is plus or minus 4.7 percentage points, 19 times out of 20, though it’s larger margin for smaller subgroups.

With Erskine-Smith on the ballot, the Liberals would win the backing of 67 per cent of respondents, the poll shows. The Conservatives would finish second at 17 per cent, with the NDP back at 12.

In the April election, Erskine-Smith was re-elected with just under 68 per cent of the vote. The Conservatives nabbed nearly 24 per cent and the NDP dropped nearly 16 points compared to 2021 to finish with roughly 7 per cent.

Mainstreet next tested Ashton as the NDP candidate, and while the party leapt over the Conservatives, it finished a distant second to the Liberals, falling 55 to 26 per cent.

Only with Lewis as the candidate would the party put up a competitive showing in the poll.

McPherson wasn’t tested as she already holds a seat in the House.

“This would be a big early boost for the federal NDP under a new leader, who have struggled to make gains since 2011 under Jack Layton,” Quito Maggi, president and CEO of Mainstreet Research said in a statement.

“This could be a good way to start for the new NDP leader, if this unfolds as expected.”

Including Scarborough Southwest, there are three federal bylections scheduled for April 13. It’s expected the Liberals will retain the riding as well as Toronto’s University Rosedale. The big question is how the party will perform in Quebec’s Terrebonne, where the Liberals initially emerged victorious last April by one vote.

That result was vacated by the Supreme Court earlier this year due to a mailing error, setting up this byelection.

Winning two of the three ridings would give the Liberals the slimmest possible majority in the House. In this scenario, the Liberals could face challenges pushing through legislation as one of the party’s seats belong to the speaker, who only votes in the case of a tie. Based on convention, the speaker votes to continue debate, meaning they must vote against non-confidence motions. But it’s unclear how the speaker would vote in other decisions.

If the Liberals won all three, the government would have 173 seats and wouldn’t need to rely on the speaker to win votes.

iPolitics will have liveblog coverage of the byelections on April 13.