The federal budget delivered by Finance Minister Bill Morneau on Tuesday is full of measures designed to reduce gender inequality, but there's one gender gap the Liberals want to keep in place — the one that wins them elections.

Morneau's third budget includes commitments on pay equity for federally-regulated employees, five weeks of extra leave for two-parent families and measures to increase the number of women working in the skilled trades and the STEM (science, technology, engineering and mathematics) sector.

Also, the government says that every item in the budget was evaluated through a process of gender-based policy analysis in order to bridge the gap between men and women in the workforce.

Another kind of gender gap worked in the Liberals' favour in 2015 — and could be a significant factor in the party's re-election chances in 2019.

In 2015, the Liberals' lead over the Conservatives among women was up to 11 percentage points wider than it was among men. A large post-election survey conducted by Abacus Data found the Liberals had a 17-point lead over the Conservatives among women, but were ahead only six points among men.

Polling by Nanos Research and Ipsos at the end of the 2015 campaign found a similar disparity between the voting intentions of men and women.

That advantage was enough to deliver Justin Trudeau a majority government. If the Liberals had led among women by the same margin they did among men, they likely would only have squeaked by with a minority win.

The Liberal caucus also boasts more women than any other caucus in Canadian history. According to the Library of Parliament, the Liberals' 50 female MPs elected in 2015 beat the previous record of 40 set by the New Democrats in 2011.

If the political gender gap helped boost the Liberals from a minority to a majority government in 2015, the party might need to lean even more heavily on its disproportionate support among women to secure re-election in 2019.

The party's edge in the polls has narrowed since the 2015. According to the Feb. 27 update of the CBC Poll Tracker, the Liberals have 38.4 per cent support to 32.9 per cent for the Conservatives.

The New Democrats trail at 17.3 per cent, followed by the Greens at 6.5 per cent and the Bloc Québécois at 3.9 per cent.

That 5.5-point Liberal lead over Andrew Scheer's Conservatives represents a loss of about two points since the last election. The Liberals' significant advantage in Quebec provides the party with a seat cushion, but the Poll Tracker still estimates the Liberals' chances of winning another majority at just 68 per cent.

That the Liberals' odds are still as good as 2:1 is largely due to the support the party has retained among women.

In seven polls conducted since the beginning of the year, the Liberals have enjoyed an average 12-point lead over the Conservatives among women. Their edge among men, however, has dwindled to nothing — there, the two parties are tied on average.

This suggests that the political gender gap may have widened since the 2015 election as the Liberals' support among men has dropped while their support among women has (depending on the poll) either held steady or dropped by a smaller degree than among men.

Nanos Research, which showed the Liberals up 15 points among women and eight points among men in its four-week rolling poll ending Oct. 23, 2015 (four days after the election), now puts the Liberal lead at 18 points among women — with the Conservatives ahead by five points among men.

The budget might go some way toward ensuring the political gender gap continues to pay dividends for the Liberals. If the party can hold its support among women through to the 2019 election, it can still emerge with a majority government — even if it loses the male vote.

Of course, attempting to address the long-standing and systemic inequities between men and women in the workforce is a worthwhile endeavour, regardless of the political payoff. An additional sum of $4.1 billion in five years in the budget aimed at improving the living conditions of Indigenous Canadians — another constituency that helped the Liberals win in 2015 — falls into the same category.

The real test will be whether the Liberals can produce results to match their rhetoric. But if they can pull that off, this budget could help the Liberals accomplish two goals at once: boosting gender equality and winning the next election.