WASHINGTON — A bipartisan group of senators neared agreement on a comprehensive immigration bill that would put illegal immigrants on a 13-year path to citizenship, officials with outside groups keeping up with the talks said Thursday.

The legislation also would install new criteria for border security, allow more high- and low-skilled workers to come to the United States and hold businesses to tougher standards on verifying their workers are in the country legally, according to outside groups and lawmakers involved.

Together, the measures would represent the most sweeping changes in immigration law in decades.

The senators in the so-called Gang of Eight were meeting for hours at a time daily this week trying to complete a deal. There were still big disagreements on some issues, but they hoped to resolve most of them before Congress began a two-week recess at week’s end. That would allow them to meet a self-imposed deadline to present their legislation next month.

“We are grappling with a number of issues, we really are, but I think we are making progress,” said Sen. John McCain, R-Ariz. “Some of these issues are very complicated.”

The group was under pressure to speed up its work. Protesters converged Thursday on the office of Sen. Chuck Schumer, D-N.Y., a leader of the group, to accuse him of breaking his initial promise to have the bill done in March.

Senate Judiciary Chairman Patrick Leahy, D-Vt., whose panel would take up the legislation, complained this week that the group was taking too long. As a result, Leahy said, his committee won’t be able to complete writing the bill itself in April, as he had hoped.

The Gang of Eight includes: Marco Rubio, R-Fla., Jeff Flake, R-Ariz., John McCain, R-Ariz., Lindsey Graham, R-S.C., Dick Durbin, D-Ill., Robert Menendez, D-N.J., Chuck Schumer, D-N.Y., and Michael Bennet, D-Colo.