Gaetan Barrette, who ran unsuccessfully for the Coalition for Quebec's Future in the 2012 election, will be the Liberal candidate in La Piniere, just south of Montreal.
The riding has been represented since 1994 by Fatima Houda-Pepin, who recently parted company with the Liberals over the party's stance on the government's proposed charter of values.
She is expected to announce on Tuesday she will run as an Independent.
Barrette said one of the reasons he has decided to run for the Liberals is the party's position on health care.
"I came here because this is, in my opinion, the best alternative for Quebecers," Barrette said. "This is the only sound economic alternative (and) it's the same thing in health care, it's the same thing in education.
Barrette said he believes the situation in Quebec has deteriorated since his last run at politics two years ago.
"Everything is worse than what it was at that time," Barrette told a news conference Monday. "It is worse in terms of the economy, it is worse in terms of health care."
Barrette also said he is worried about the possibility of another referendum on sovereignty.
"That has to stop and if this is to stop, it has to be through a majority Liberal government in this province," he said.
Barrette is stepping down as head of the group that represents specialist doctors.
Premier Pauline Marois, who heads a minority government, is widely expected to call an election this week or next for April 7 or 14.
Quebec solidaire, a left-wing sovereigntist party, announced four candidates on Monday, including labour activist Claude Genereux.
Francoise David, one of the party's two members in the national assembly, will also see her sister running in the election, although Helene David will be seeking to get elected as a Liberal.
Francoise David said she and her sister come from a very political family.
"There are people of all political stripes," she said. "This never stopped us from having very warm family gatherings with lots of good debates."
She recalled there are other such families in Quebec, citing the Johnsons, whose patriarch was a Union nationale premier while sons Pierre Marc and Daniel were respectively Parti Quebecois and Liberal leaders.
"Now you have the David sisters," Francoise David said. "It shows the times are changing. I don't see any problems. I'm sure our Easter dinner will go well."
Also on HuffPost