YORBA LINDA, Calif. — In the hours after President Richard Nixon delivered a public Watergate address as scandal exploded, two future presidents called him to express their private support, according to audio recordings released today.

The April 30, 1973, calls with Ronald Reagan and George Bush Sr. were captured on a secret recording system that Nixon used to tape 3,700 hours of conversations between February 1971 and July 1973.

The final chronological installment of those tapes — 340 hours — were made public by the National Archives and Records Administration, along with more than 140,000 pages of text documents. Seven hundred hours remain sealed for national security and privacy reasons.

California Gov. Ronald Reagan called late in the evening of April 30 to support Nixon after the 37th president delivered a landmark speech about the Watergate scandal, which was rapidly ensnaring him.

Two top White House staffers and close Nixon confidants, H.R. Haldeman and John Ehrlichman, had resigned earlier in the day, as well as Attorney General Richard Kleindienst as the scandal picked up speed. White House counsel John W. Dean III was also fired that day.

Reagan told Nixon the speech was the right one to make and sympathized with the staff exodus.

“I just want you to know, we watched and my heart was with you. I know what this must have been and what this must have been in all these days and what you’ve been through,” Reagan said.

“You can count on us, we’re still behind you out here and I wanted you to know that you’re in our prayers.”

That same evening, George Bush Sr., who had recently been appointed chairman of the Republican National Committee, called to say he had watched the speech with “great pride.”

This time, however, an angry and exhausted-sounding Nixon complained to Bush about the reaction from TV commentators.

“The folks may understand,” Nixon said, before adding later: “To hell with the commentators.”