WASHINGTON — On the brink of a painful government shutdown, the Obama administration readied furlough notices for hundreds of thousands of workers Friday as Republican and Democratic leaders accused each other of refusing to give ground on a deal to keep operations running.

By midday Friday, most employees of the federal workforce had been told whether they had been deemed essential or would be temporarily laid off from work if lawmakers failed to reach an agreement by midnight.

In the event of a shutdown, official furlough notices would begin going out by email, by written letter or in person.

Many workers would be allowed into their offices for up to four hours on Monday to finish tasks, but that would be it.

Senate Majority Leader Harry Reid accused the Republicans of blocking a compromise because they were determined to make it harder “for women to get cancer screenings.” That was a reference to money for Planned Parenthood, an organization Republicans assail as the country’s largest provider of abortions.

Reid’s main antagonist in the long-running negotiations, House Speaker John Boehner, said spending cuts — not social issues — were blocking agreement to prevent a shutdown.

“Most of the policy issues have been dealt with, and the big fight is about spending,” Boehner said Friday afternoon.