Tunisia’s president dissolved Parliament on Wednesday, after lawmakers voted to block emergency powers he had given himself last year, trying to harden his sole grip on the government and courting what could be the country’s severest political crisis since the 2011 revolution.

Last July, amid mass protests over poverty, corruption and the handling of the pandemic, President Kais Saied suspended Parliament, dismissed his own prime minister and other officials, and granted himself extraordinary powers, in what his critics denounced as a coup.

But on Wednesday, lawmakers held an online meeting, defying Mr. Saied’s warning that the session was illegal, and a majority voted against his power grab, which they said violated the country’s Constitution.

Shortly afterward, in a meeting of his National Security Council, the president said the country was facing “unusual” times.

“We are living today, unfortunately, through a coup attempt, but it has failed,” he said, then announced that he was dissolving Parliament “to protect the government, the institution and the Tunisian people.” His office posted video of his statement on Facebook.

His government said it would investigate the lawmakers who had taken part in Wednesday’s session.

In 2011, a popular uprising in Tunisia toppled the dictator Zine el-Abidine Ben Ali after 23 years in power — the first of protests in the region that came to be known as the Arab Spring. But Tunisia’s was the only lasting democracy to emerge from that heady upheaval, and it has been a troubled and fragile experiment in popular rule.

Mr. Saied, a former constitutional law professor who was seen as being above the mire of politics, was elected in a landslide in 2019. But he has become steadily more autocratic, ruling by decree, jailing opponents, suspending parts of the Constitution, dismissing the Supreme Judicial Council and restricting press freedom.

Political unrest continues to shake the country, stoked by partisan divisions and a sinking economy. The president has promised to have a new Constitution drafted and put to a referendum this year, followed by the election of a new Parliament.