The Arlington County Republican Party will hold a local version of a primary to select candidates to support in the November races for sheriff, treasurer and two seats on the County Board.

The County Board race is critical to Republicans since candidates endorsed or nominated by county Democrats have won the last three elections and now control three of the five seats.

The voting, officially called a canvass, will take place today from 2 p.m. to 8 p.m. at the Lyon Village Community House. Traditionally the poll attracts party regulars. However, any county resident who signs a written pledge to support candidates supported by the Republicans can cast a ballot.

The candidates are running as independents, instead of seeking the party's nomination, so that they can draw support from the large number of Arlington residents who are federal employes and are barred by the Hatch Act from working for party nominees.

Some of the candidates themselves are federal employes and would not be able to run as Republicans, so they are seeking the party backing as independents.

In the race for two seats on the County Board, three candidates are competing for the Republican endorsement. Incumbent board member Walter L. Frankland Jr. is expected to clinch the Republican's endorsement of his campaign for a third four-year term on the board.

School Board member Michael E. Brunner, an Agriculture Department executive, and John Marshall, an Education Department manager, are also competing for the party endorsement for the County Board seat vacated by Dorothy T. Grotos, who was Frankland's running mate for the past two elections. Marshall is past chairman of the county's fiscal affairs advisory commission.

At the May 7 County Board meeting, Frankland supported an unsuccessful motion by Grotos to reappoint Brunner to the School Board. Frankland later said that he believed Brunner to be the most qualified of the School Board candidates and denied that his action was an indication that he wanted Marshall as his running mate.

Grotos has decided to seek the county treasurer's job and will face William H. Nehrke, a program officer for the Naval Supply Systems Command, for the endorsement.

In the sheriff's race, John Baber, Charles Bonneville and David Ryan have been conducting spirited campaigns that last week included charges of plagiarism. Bonneville accused Baber of plagiarizing campaign material and Ryan countered with the same charge against Bonneville. Bonneville denied the accusation, as did Baber.

Commonwealth's Attorney Henry E. Hudson, an independent, is seeking the party's endorsement for reelection but is running unopposed.

Only one candidate, William S. Miller, will appear as a Republican on this fall's ballot in Arlington. Miller, a law firm librarian, is seeking the 47th District state delegate seat held by Democrat James F. Almand.

The county Republican committee will meet tonight after the polling is completed and the results of the voting will be announced. At that meeting, World Bank employe Bonnie Newlon is expected to ask the Republican Committee meeting to endorse her independent candidacy for a race against Democratic Del. Mary Marshall in the 48th District. Newlon did not file her election petition in time to be included in the voting today.