Supporters of the Pakistan Tehreek-e-Insaf blocked roads near the capital on Tuesday, disrupting traffic and forcing schools to close, as they protested against a bid to assassinate their leader at a recent anti-government rally.
Imran Khan, who has been pressing for a general election since he was ousted as prime minister after losing a confidence vote in parliament in April, was shot at the rally last Thursday. He is recovering from leg wounds.
"People are finding it very hard to go to work," said police official Yawar Ali. "Families have been stuck in the traffic for hours. We've even got reports that the protesters have not let ambulances pass."
PTI supporters began their protests on major roads around Islamabad late on Monday. They have blocked the highway to Islamabad's international airport and the ones linking the capital to the cities of Lahore and Peshawar.
Television footage showed the supporters burning tyres as they set up protest camps across roads.
The government ordered all state and private schools to shut for the day, according to an order seen by Reuters.
The PTI announced late on Monday that the march would resume on Thursday at the place where Imran was attacked, and he would lead it virtually.
The political tension comes as the country is grappling with economic turmoil exacerbated by recent flooding that the government estimates caused economic losses worth $30 billion.