The move, a bid to reform the Senate, blindsided both Liberal senators and veteran political observers.
It will see some life-long Liberals and key party operators and fundraisers effectively expelled from the party's caucus and forced outside its inner circles.
The Liberal leader is scheduled to talk to reporters in the foyer of the House of Commons starting at 9:30 a.m. ET.
Trudeau's surprise move Wednesday morning came as all parties held their caucus meetings in Ottawa.
Those meetings typically include both MPs and senators.
There are currently 32 Liberal senators who sit in the Upper House as official members of the Liberal Party and represent the party's positions and political interests.
Those senators also sit and vote on Senate committees that do important political work reviewing legislation.
It's not yet clear how, or even if, the Liberal Party intends to maintain its political power inside the Senate.
The Senate scandal that has dominated political news in Ottawa for more than a year has had political implications for both the Liberal and Conservative parties.
Although most of those senators under investigation are former Conservatives, the Liberals have not escaped being tarred by the scandal's politically sticky brush.
Former Liberal senator Mac Harb has been accused by the RCMP of committing fraud by filing inappropriate expense claims, according to documents filed in Ottawa court.
A Senate committee investigating senators' expenses ordered Harb to repay more than $230,000.
He retired in August after paying it back.
Mobile users can watch the announcement here.