Pressure is building on the prime minister and his office as a growing number of anxious Liberal MPs are co-ordinating efforts to force Justin Trudeau to step down as Liberal Party leader, multiple sources have told CBC News.

Disgruntled Liberal MPs held a series of meetings to discuss a path forward for the party since the surprising Toronto-St. Paul’s byelection loss in June.

Those talks accelerated with Parliament’s return and the Montreal byelection loss. They escalated further this week with the prime minister and his chief of staff, Katie Telford, out of the country for a summit in Asia.

Some MPs are being asked to sign their names to what amounts to a pledge to stand together in calling for Trudeau to resign, multiple sources said.