Opposition Leader Bill Shorten has been confronted by an Anglican priest over comments linking opponents of same-sex marriage to bigoted views and homophobia.

Canberra priest Ian Powell approached Mr Shorten after the traditional church service to mark the opening of Parliament on Tuesday, as Labor comes under pressure to support the Turnbull government's planned plebiscite on same-sex marriage.

The Greens and Nick Xenophon's party have confirmed they plan to block the required enabling legislation in the Senate, with Labor expected to announce its opposition when the government finalises its plans for a February vote.

Rector Powell took issue with comments Mr Shorten made during the election campaign, linking a fatal shooting at a gay nightclub in Orlando, Florida with the plebiscite campaign, saying it could "give haters the chance to come out from under the rock".