RIO DE JANEIRO  Argentina enacted a controversial law on Saturday that gives the government more control over the broadcast media, handing a victory to the president and her husband, the country’s former leader, who have blamed media coverage they call biased for many of their political woes.

After more than 19 hours of debate, the Senate approved the media bill early Saturday morning, by a vote of 44 to 24, without modifications. President Cristina Fernández de Kirchner had proposed the bill to replace a dictatorship-era law that allowed the concentration of media power in the hands of a few companies. The government said the changes, which include forcing companies to shed some of their media outlets, would diversify the public airwaves.

Mrs. Kirchner signed the bill into law later in the day.

While many media experts have said the old law was outdated and in need of reform, analysts say the move by the Kirchner government seemed intended to give the executive branch significant discretion in the regulation of broadcasters.

Carlos Lauria, senior program director for the Americas at the Committee to Protect Journalists, said the new rules could restrict freedom of expression, in particular a provision that gives the president the authority to appoint most members of a new broadcast regulatory body.