Lt. Gov. John N. Dalton, the Republican nominee for governor, charged yesterday that his opponent, Henry E. Howell would stop the construction of I-66 if he is elected governor, but Howell's campaign manager immediately denied the charge.

"I-66 will be built from the beltway to the Potomac before I go out of office." Dalton said two groups in Northern Virginia yesterday. "I charge he's going to stop the contruction of I-66 if he's elected."

Howell's campaign manager, Willie Rosendahl, said that was "untrue and inaccurate. Henry is in favor of completing I-66 as a transport need that would do the greatest good for the greatest number of people. He's in favor of the concept; however he's not saying exactly where it should be routed."

The I-66 controversy has been dragging on for nearly 20 years. Those opposed to the highway say it willruin neighborhoods, increase pollution, and cost money that should be spend on public transportation. Construction began a month ago, but opponents are seeking to block further construction before the Fourt U.S. Circuit Court of Appeals in Richmond.

Howell, in appearances here during the primary and more recently, has refused to take either an affirmative or negative position on the issue, saying that if he lived in Prince William County he'd be for it, but if he lived in Arlington he'd be against it. Rosendalh said that Howell has always favored completion and his statement yesterday does not represent a switch.

Dalton officiated at the opening of his Northern Virginia headquarters yesterday, where about 250 people, a decorated water truck, and a calliope were gathered for a festive opening. Dalton's six-room headquarters near Baileys Crossroads includes a bank of 48 telephones.

As local Republican elected officials such as Fairfax County Board of Supervisors Chairman Jack Herrity looked on, Dalton inaugurated the phone bank by calling a few voters for the benefit of television cameras. His first few calls were unanswered but finally he reached a voter.

"Is this Miz Irish? I'm John Dalton, candidate for governor . . . Sure hope we can count on your support. Oh. good, good. . . Are y'all going to be able to get to the polls?"

Attorney general candidate J. Marshall COleman, was introduced to the crowd at the headquarters opening by the man who ran against him for the nomination, del. Wyatt B. Durrette. "I read in the paper where the other candidate for governor (Howell) said he would hire his own attorney if I get elected," Coleman said. "Well, if by some fluke he sould get elected, I plan to hire my own governor . . . that was a joke."

Dalton told the audience that contributions - he called them "receipts" - had been pouring into his headquarters this week on the average of $15,000 a day.