OTTAWA - When the dust settles Monday evening, voters will have left only three candidates standing in a triad of federal byelections that have gained a lot of national attention.

A tug-of-war in Calgary Centre will likely be the most watched contest, where Conservative candidate Joan Crockatt is in a tougher-than-expected fight.

The riding became vacant when Conservative incumbent Lee Richardson quit to work for Alberta Premier Alison Redford.

"The momentum seems to have gone, at least up until recently, in the most recent polls to Harvey Locke, the Liberal candidate," Mount Royal University's Lori Williams told Sun News Network.

Locke's campaign, however, suffered from a lot of friendly fire in the last week of the campaign that revived memories of the hated National Energy Program.

Liberal MP David McGuinty apologized and resigned his critic's post after telling QMI Agency that Conservative MPs should "go back to Alberta."

A day later, news broke of Grit leadership candidate Justin Trudeau's rant in a 2010 Quebec television interview about "too many" Albertans running the country.

Less likely to be a close race is the byelection in Durham, east of Toronto, where Conservative Erin O'Toole is expected to retain the seat vacated by troubled Tory cabinet minister Bev Oda.

The race has seen some controversy after Liberal candidate Grant Humes slapped his party's logo over the silhouette of a soldier on his lawn signs.

Meantime, the NDP's Murray Rankin is considered likely to hold the riding of Victoria, B.C., for his party, fighting off challenges from the Green Party, Liberals and Conservatives.

Victoria voters voted solidly NDP in the 2011 election. NDP MP Denise Savoie left politics in August for health reasons.