CARACAS, Venezuela — An anti-government strike paralyzed parts of Venezuela Thursday, as the nation’s crisis risked spiraling ahead of a contentious vote that many fear could move the country further down the path of authoritarian rule.

President Nicolás Maduro played down the strike, but in many districts, businesses were shuttered and protesters blocked roads as the opposition sought to stage Venezuela’s largest general strike since 2002.

In Caracas, the strike was most pronounced in the eastern neighborhoods, a middle- and upper-middle-class bastion. There were also reports of government troops firing tear gas at demonstrators and strikers. In the western city of Maracaibo, witnesses reported closures and said National Guard forces lobbed tear gas at protesters.

The effort unfolded as Maduro’s unpopular socialist government faced escalating international pressure to back off the special election on July 30. The vote would elect a body to rewrite the 1999 constitution and further squelch the opposition-controlled National Assembly in a move widely viewed as a power grab.

The Trump administration, pressed by prominent U.S. lawmakers, is weighing sanctions up to and including bans on Venezuela’s all-important oil exports if the vote is not called off. In an official report, Luis Almagro, secretary general of the Organization of American States, said Wednesday that there are fears that the situation in Venezuela “will escalate into a bloodbath.”