HALIFAX -- Byelections in three Nova Scotia constituencies will be a mid-term test of the province's majority Liberal government, a political science professor said Monday.

Jeff MacLeod, chairman of political and Canadian studies at Mount Saint Vincent University in Halifax, said Tuesday's byelections will put Premier Stephen McNeil's spring budget to the test.

"It's the government that's most on trial here," said MacLeod in a phone interview.

"It's a mid-term test. There are three seats and they should be competitive in all three... not so much to win all three but are they running strongly in seats that they haven't held before?"

Seats are up for grabs in the Cape Breton ridings of Sydney-Whitney Pier and Cape Breton Centre, which were previously held by NDP members Gordie Gosse and Frank Corbett.

The Dartmouth South riding has been vacant since the death of Liberal member Allan Rowe in March.

MacLeod said if the government were to lose the race in that constituency, it would be a clear indication that fortunes are changing for the party.

He said because there are no incumbents in any of the ridings and some of the candidates' names may not be recognizable to voters, he believes the public will be voting for the political party rather than the politician.

"You have people with limited experience in politics running, so really it's going to be the party label and the leader's reputation that's probably going to determine many of the votes," said MacLeod.

"From that perspective, it will be a really interesting test because it could be a true test of government support or lack thereof."

But Don Mills, chairman and CEO of Corporate Research Associates, disagreed that the byelections were a mid-term assessment of government support.

Mills said the races are inconsequential to the government's 32-seat majority.

"So I don't think there's a lot of interest in them as a result," said Mills. "It's really the party that's most effective at getting their voters out that stands the best chance of winning those seats."

MacLeod said he expects voter turnout to be low because there are no incumbents and lots of people are away on summer vacation, among other factors.