WASHINGTON — Speaker Nancy Pelosi of California on Friday announced she was instituting a higher pay scale for House staff, moving for the first time to set a floor on annual wages and boosting the maximum salary in a bid to improve working conditions on Capitol Hill and retain congressional staff.

Under pressure from aides who have been increasingly vocal about long hours, poor pay and a difficult work environment, Ms. Pelosi established a minimum annual salary of $45,000 that she said must be implemented by Sept. 1. She also boosted to $203,700 the cap on what staffers can earn, a slight increase from the $199,300 maximum she announced last year when she did away with a rule that dictated that no aide could earn more than the $174,000 salary for members of the House.

And Ms. Pelosi said the House would vote next week on a resolution that would grant aides legal protections to form a union, more than a quarter-century after Congress approved legislation to allow staff to bargain collectively. It is likely to pass with mostly, if not all, Democratic votes, after which the House could carry out the change.

The moves come as aides have pressed for Congress to address inequities in its work force and find ways of stemming a staff exodus as aides leave the institution to find better pay and treatment.

Frustrations with the demanding environment on Capitol Hill — long and unpredictable hours, low pay and paltry benefits, a lack of diversity and often mercurial bosses — have been exacerbated in recent months by the challenges of the pandemic and an atmosphere of fear and mistrust that has lingered in the aftermath of the Jan. 6 riot.

A January analysis published by Issue One, a bipartisan political reform organization, found that the median salary of Washington-based congressional staff in 2020 was $38,730 for a staff assistant, typically an entry-level position. (A living wage in Washington at the time, according to data from the Massachusetts Institute of Technology, was $42,610 for an adult with no children.)

As part of the sprawling government funding package that became law in March, House lawmakers received a 21 percent increase in their office budgets, the largest such boost since 1996.

While lawmakers have the discretion to set their own budgets, Ms. Pelosi and other Democratic leaders who spearheaded the increase, including Representatives Steny Hoyer of Maryland and Hakeem Jeffries of New York, have urged that the additional funds be used to increase staff pay. The new minimum salary will effectively mandate that at least some of the additional money be devoted to staff pay.

“With a competitive minimum salary, the House will better be able to retain and recruit excellent, diverse talent,” Ms. Pelosi wrote in a letter to lawmakers announcing the change. “Doing so will open the doors to public service for those who may not have been able to afford to do so in the past. This is also an issue of fairness, as many of the youngest staffers working the longest hours often earn the lowest salaries.”

Earlier this year, House staff announced they had formed a union to push for the rights and protections that other federal workers already have, amid a series of high-profile unionization efforts across the country. The effort has received backing from Ms. Pelosi and Democratic leaders as well as President Biden and major labor groups.

“When the House passes this resolution, we will pave the way for staffers to join in union, if they so choose,” Ms. Pelosi wrote. “Congressional staffers deserve the same fundamental rights and protections as workers all across the country, including the right to bargain collectively.”

The group has remained anonymous, citing the lack of legal protections on Capitol Hill. But in a statement, the Congressional Workers Union applauded Ms. Pelosi’s decision to bring up legislation that would provide such safeguards.

“With this vote, every member of Congress will have the opportunity to grant their own workers the right to organize and bargain collectively, free from retaliation,” the group wrote. “We welcome and look forward to the vote, and we expect that every member who has stood up for workers’ rights will vote for our right to form a union.”

As part of an effort to ensure Congress was no longer exempt from civil rights and labor laws extended to the private sector, lawmakers approved the Congressional Accountability Act in 1995. That legislation gave congressional employees the right to unionize. But lawmakers soon balked at passing rules that would give necessary legal protections, including rules barring retaliation against staff who sought to organize, effectively stymying unionization efforts.

The resolution that is expected to pass next week, sponsored by Representative Andy Levin, Democrat of Michigan, would for the first time extend to House employees the same labor rights and protections other federal workers enjoy, including protection from retaliation. It would apply to all House aides, according to a draft reviewed by The New York Times.

In an interview, Mr. Levin said it was “critical that we lawmakers have walked the walk, affording all workers in this country the freedom to form unions and bargain collectively.”

“This is a great moment for really the broader effort of workers all across this country to organize and bargain for a better life,” he added.

The measure applies only to House staff aides. Unionization efforts have not gained as much traction in the Senate, which would have to pass its own resolution to afford staff aides legal protections for collective bargaining.