Richmond lawyer Richard Cullen, a partner in one of the state's most influential law firms, has emerged as one of the leading candidates for the post being vacated by U.S. Attorney Elsie L. Munsell, according to Republican officials.

Cullen, 37, is a close associate and law partner of former Gov. John N. Dalton, a Republican. Dalton said today that he had urged Sen. Paul S. Trible (R-Va.) to recommend Cullen to President Reagan.

Cullen's is only the second name to be mentioned for the prestigious Eastern District job, which includes overseeing federal prosecutors and civil attorneys in an area extending from Northern Virginia to Richmond and the populous Hampton Roads-Norfolk area.

Arlington Commonwealth's Attorney Henry E. Hudson, 38, also is being considered for the $68,000-a-year post. Trible has not yet made a recommendation but has indicated he wants to act quickly to enable Reagan to fill the post when Munsell's term ends later this month. Munsell, who has been troubled by controversy through much of her four-year term, has asked Trible not to reappoint her.

Cullen, a member of the firm of McQuire, Woods & Battle, has drawn the support of Richmond's Democratic Mayor Roy A. West, as well as former Republican Rep. M. Caldwell Butler of Roanoke and J. Marshall Coleman of McLean, the GOP candidate for governor in 1981 and now a Northern Virginia lawyer.

"I just think he would be a super U.S. attorney," Dalton said of Cullen today. "I'm doing everything I can to help him." Dalton said that Cullen, a nine-year member of the firm's litigation section, would be the first Richmond area lawyer to be named to the position in 30 or 40 years.

Hudson, who is thought to be favored by U.S. Attorney General Edwin Meese, was unavailable for comment yesterday. Hudson is chairman of a pornography commission established by Meese and was in Florida for hearings.

A conservative first elected in 1979, Hudson has drawn both praise and criticism for his aggressive style as Arlington's chief prosecutor.