Vague objections to the system solidified into firm opposition.

先前对这一制度不大明朗的反对演变成了坚决的抵制。

《牛津词典》

We express strong dissatisfaction and firm opposition to it.

我们对此表示强烈不满和坚决反对。

youdao

We express our firm opposition and strong condemnation to that.

我们对这种行径予以坚决反对和强烈谴责。

youdao

The declaration called on the people of the South to unite and be firm in their opposition to the North.

VOA: special.2009.03.12

Republicans stood united in opposition to the legislation, claiming it would increase the national debt, and put the government in firm control of the health care system.

VOA: standard.2010.03.22

Even some who had initially declared firm opposition to the bid softened over time.

WSJ: Murdoch Wins His Bid for Dow Jones

On Tuesday, China expressed firm opposition to the test but called for a calm response by all sides.

NPR: Obama Calls NKorea Nuke Test 'Highly Provocative'

The Foreign Ministry expressed "firm opposition" to Pyongyang's third test in defiance of UN Security Council resolutions, but did not specify further action.

BBC: China media: Pyongyang pressure