He'd rather not discuss it publicly, but friends say Virginia Gov. John N. Dalton would like nothing better than to be Ronald Reagan's running mate this fall.

The conservative Republican surprised his own staff two months ago when, answering a reporter's question, he said he would accept the vice presidential slot if offered. Taking the hint, supporters from Dalton's native 9th Congressional District in southwest Virginia drew up a resolution boosting the governor as the state's favorite son candidate and presented it to the GOP state convention, which opened today.

A slightly embarrassed Dalton had the resolution withdrawn this afternoon, saying in an interview that Reagan should be free to choose his own running mate. But Dalton also allowed he still was interested in the job.

"I think it would be a high honor for anybody to serve as vice president of the United States," he said, adding that he had not talked to anyone in the Reagan camp about the job.

Some other Virginia Republicans privately scoff at the idea that Reagan, a former governor with little foreign policy or Washington experience could enhance his ticket with Dalton, who has similar gaps in his ressume.

"The governor is dreaming," said one Republican. "Reagan needs him like a hole in the head."

Other Republicans say they still plan to push Dalton at the national convention in Detroit next month. "Reagan needs a southern governor and he needs a good conservative," said Billy W. Frazier, 9th District GOP chairman and a Dalton ally. "John Dalton's been a great governor and he'd make a great vice president."

The Reagan people say they have not ruled out Dalton -- or anyone else -- as the vice president nominee. A spokesman said today that the campaign has commissioned the Decision Making Institute, a Los Angeles polling firm, to test public reaction to 18 possible nominees. The names of the list have not been made public, and the spokesman would not disclose if Dalton was one of them.

The Dalton resolution was about the only controversial issue at the state GOP convention which was supposed to draw about 7,000 people to Richmond.Officials said George Bush's withdrawal from the presidental race and Reagan's ascendancy helped keep today's crowd below 1,000.

"A lot of people who had planned to come are going to stay home and mow their lawns," said John J. Coakley of Fairfax, who was Bush's state coordinator until he dropped out of the race last month.

Reagan is assured of all of Virginia's 51 delegates to the national convention but party officials still expect a struggle tomorrow over who will be tapped for the 21 at-large delegate seats to be chosen by the convention.

Ideological purity is the issue, with some Reagan stalwarts working to keep all former Bush supporters and neutral Republicans off the slate. The Reagan people and state party leaders are expected to meet through the evening to attempt to hammer out a compromise and avoid a floor fight on the issue.

"We try to do everything in a nice orderly fashion," said state party chairman Alfred C. Cramer, "We're not Democrats, we're Republicans."

The question of ideological purity was also the focus of today's keynote address from conservative Rep. Robert E. Bauman (R-Md.). After blasting President Carter as "our national joke," Bauman took swipes at two Republican vice presidential possibilities, Sen. Howard Baker of Tennessee and Sen. Richard Lugar of Indiana.

Although he mentioned no name, Bauman clearly had Baker in mind when he warned that Reagan's running mate should not be a member of Congress guilty of "foreign policy collaboration" with the Democrats. And he implicated Lugar when he warned that "no one who helped to give Communist Nicaragua $75 million in American money should be a heartbeat away from the president."