PORTLAND, Ore. (AP)--Striking nurses reached a tentative agreement Wednesday with Oregon Health & Science University aimed at ending a 53-day walkout.

The agreement with the Oregon Nurses Association was reached after a 15-hour negotiating session. If approved, it will end a walkout that included loud union rallies and picketing, as well as charges and countercharges over the use of replacement workers and the quality of patient care during the strike.

"Both sides traveled a bit. Both sides were willing to compromise," said Jim Newman, spokesman for the university, which operates two of Oregon's top hospitals, Oregon Health & Science and Doernbecher Children's Hospital.

"In the beginning, we were very far apart," he said.

Both the union and the hospital are recommending ratification, he said. Nurses will vote on the proposed contract Sunday and could return to work as early as Feb. 13.

Union spokeswoman Claudia Brown said the nurses were relieved that the strike appeared to be over.

"It has been a very long strike, and the ONA is very proud of their OHSU members. They took a united stand, and it has paid off in ways that will benefit everyone," Brown said.

The latest mediation session -- the fifth attempt to end the strike since about 1,300 nurses walked out Dec. 17 -- began Tuesday and ran into Wednesday morning.

The agreement provides for 7 percent raises in each of the contract's first two years, plus a minimum 6.5 percent raise in the third year, according to university officials.

The proposed new contract also includes payments to full-time nurses to offset the costs of out-of-pocket insurance costs and other benefits.