Anne Arundel County Executive O. James Lighthizer resigned yesterday as vice chairman of the state Democratic Party, citing differences with party Chairman Rosalie Reilly on fund raising and the use of paid consultants in the 1988 election year.

Reilly and Lighthizer were appointed to their party posts just five months ago by Gov. William Donald Schaefer.

The two have been feuding ever since.

Reilly said last night that Lighthizer called her yesterday and told her of his decision to quit.

According to party sources close to the county executive, Lighthizer informed Schaefer of his decision Wednesday and mailed a strongly worded letter of resignation to members of the State Central Committee late yesterday, just before leaving for a trip to London.

Sources familiar with the letter said Lighthizer cited his disagreement with Reilly's leadership.

Lighthizer, who was asked by Schaefer to raise funds for the party in 1988, has wanted to hire Potomac Survey Research Associates, a Montgomery County consulting firm run by prominent political pollster Keith Haller.

The firm set up a sophisticated voter data base for the party in the 1986 elections called Maryland Campaign Central and sold the information to Democratic candidates.

Some of the fees paid by the 102 candidates who used the system went to the party.

Reilly has opposed the hiring of any outside consultant at this point in the campaign, arguing that the party does not have the funds and that next year's expected challenges from Republicans do not warrant such spending.

Party activists have said that the battle between the two boiled down to a contest of wills between people with vastly different styles and party credentials.

Reilly, 57, is Montgomery County register of wills and has long been active in party vote efforts.

Lighthizer, 40, is the aggressive administrator of a fast growing county and is not used to playing second fiddle.

Lighthizer informed Schaefer last week of his intention to quit, party sources said, but the governor asked him to wait until this week before making his decision final.