Andrew Scheer launched his campaign Wednesday for the federal Conservative Party's leadership, backed by 20 MPs and senators who support his bid.

Scheer, who served as House Speaker for the four years prior to the last election, framed his campaign as one that's positive and one that focuses on conservative values like low taxes, respect for families and economic growth. That seems to have attracted him the most caucus support so far in a race that features seven declared candidates. Another three MPs are also considering bids, as well as two former MPs who were defeated last October.

The 36-year-old MP for Regina-Qu'Appelle said the race means he'll spend a lot of time away from his wife and five children, but said the sacrifice is worth it so the Conservatives can defeat the Liberals in 2019.

"I cannot let Justin Trudeau do to my children what his father did to my generation," Scheer said.

Scheer outlined his vision for the Conservative Party, suggesting he'd keep the faith of long-time supporters while adopting a fresh approach.

"Conservatives do not win when we abandon our principles. We do not need to change who we are. We're the party of prosperity, not envy. The party of hope for the middle-class, not sweetheart deals for insiders and the elite. A party with a clear and distinct vision for our country, not a pale imitation of the Liberals," he said.

Scheer is likely to appeal to social conservatives unhappy with the controversy over the assertion by Kellie Leitch, another leadership candidate, that new Canadians should be screened for anti-Canadian values.

"I would hope that all the conversations we have about this issue or others always maintains the image of the Conservative Party as a positive, welcoming, inclusive party that accepts and celebrates the contributions that new Canadians have made to this country," he said.

While outlining his bid, Scheer faced repeated questions about his own values, including whether he would like to see restrictions placed on abortion and gay marriage, two measures he'd voted in favour for in the past. Scheer said caucus and party unity are his priorities, and it's important that every kind of conservative feels comfortable in the party.

"As leader of the Conservative Party, as prime minister of Canada, those subjects will not be reopened [by] the Conservative government," he said.

Under Stephen Harper, backbencher Conservative MPs brought forward motions and bills to reopen the abortion debate. Asked whether he would let MPs try that method, Scheer referred to his own ruling as Speaker that reminded MPs they have a right to speak in the House regardless of whether their leader gives them permission. He says he'd instead encourage his caucus to focus on what unites them.

"There are issues that we can bring up on a wide spectrum of things that don't have very good odds of passing in the House, that would divide our caucus. And it's not good for the team to do things like that. It doesn't advance the cause of the things that we believe in, it doesn't advance the cause of the party to be focusing on those things that even conservatives can't agree on," Scheer said.

The Conservative Party will choose a new leader on May 27, 2017.