It's a year in Maryland politics that shows the power of incumbency, and the best example is at the top of the ballot. Gov. William Donald Schaefer seems to be overseas as much as he is on the campaign trail. When Marylanders vote in the Sept. 11 primary election, they will face an extensive ballot but few competitive races, at least at the state and congressional levels. Things could heat up by the November general election, but the prospect now is for a low-key season. Voter registration is lagging, and, unlike the hotly contested gun ban of two years ago or the gubernatorial race of 1986, no campaign has ignited voters statewide.

Leading the Democratic field is Schaefer, who has banked nearly $2 million in contributions and maintained a full schedule of state business that included a trip to Taiwan less than a month before the primary.

So seemingly confident is Schaefer that his reelection effort has been cloaked not in standard rhetoric, but in a campaign of civic boosterism that presumes he will be around for four more years. The "Campaign for Maryland" is promoting civic activism on the environment, education and substance abuse, and promoting the reelection of Schaefer and Lt. Gov. Melvin A. Steinberg.

Challenging him in the Democratic primary is Fred Griisser, leader of the group that unsuccessfully opposed the state's effort to prevent the sale of cheap handguns, a law backed by Schaefer. Griisser, who has raised only a few thousand dollars, says his campaign seeks to give a choice to "normal" voters, ones he contends are tiring of Schaefer's spending and perceived arrogance.

On the Republican side, the GOP was set to challenge Schaefer with William S. Shepard, a retired Foreign Service officer from Potomac who was expected to offer an articulate attack on Schaefer's first term. But when he named his wife as his running mate for lieutenant governor, the deal came undone; perennial GOP challenger Ross Z. Pierpont, a retired surgeon from Baltimore, entered the race minutes before the filing deadline, saying Maryland should not be a "one-family state."

Pierpont has put a kink in Shepard's fund-raising, and party regulars have not ruled him out as a possible victor in the primary. Shepard, meanwhile, has stayed a course of bull roasts and candidate forums, trying to spread his name outside of Montgomery County, where he ran unsuccessfully for Congress in 1986.

Among the statewide issues of note this year are taxes, growth and abortion.

Tax limitation measures are scheduled for the general election ballot in four counties -- Montgomery, Howard, Anne Arundel and Baltimore -- but a recent court decision may render them meaningless. Growth is also the main issue in Montgomery County Councilman Neal Potter's challenge of County Executive Sidney Kramer.

Abortion appears to be having a more selective impact, but heavy nonetheless in the districts where it is an issue. In Democratic primaries in Montgomery and Prince George's counties, abortion-rights candidates are mounting challenges to four antiabortion senators who participated in last spring's filibuster of legislation that would have guaranteed continued access to abortion.

Neither Maryland U.S. senator is up for election this year, and incumbents have the advantage in seven of the eight contests for U.S. House seats.

The one exception is in the 1st District, where U.S. Rep. Roy P. Dyson is facing a spirited primary challenge after controversy two years ago over the suicide of his chief aide and the disclosure of Dyson's close ties to defense contractors.

He is challenged by Del. Barbara O. Kreamer (D-Harford), who has campaigned against Dyson's reliance on political action committee funds and his opposition to abortion, and two other Democrats.

For the GOP, the 1st District presents the best chance to translate the registration gains of the last 10 years into a victory. Eight hopefuls will square off in the primary, a situation that has left Republican officials saying they are enthusiastic about the interest but worried that an intraparty fight could weaken the eventual nominee.

Other state officials up for reelection are Attorney General J. Joseph Curran Jr. and longtime Comptroller Louis L. Goldstein. Both are Democrats and face nominal opposition.

In Prince George's County, Rep. Steny H. Hoyer, a nine-year veteran of the House of Representatives, is being challenged in the Democratic primary by first-time candidate Abdul Alim Muhammad, a physician and the national spokesman for the Nation of Islam.

In the county's state legislative delegation, two Democratic incumbent senators, Arthur Dorman and Thomas Patrick O'Reilly, face no primary opposition. Two others are being challenged by delegates seeking to move to the upper chamber: Sen. Frank J. Komenda is facing Del. Gloria Lawlah, and Sen. Albert R. Wynn is being challenged by Del. Juanita Miller. And in the 24th District Senate race, incumbent Democrat Decatur W. Trotter is being challenged by Tommie Broadwater Jr., the previous occupant of that seat.

There are no Republican primaries for either the Senate or the House of Delegates. In the House races on the Democratic side, there are primaries in every district except 13B in the far northern part of the county.

On the county level, council member Floyd E. Wilson Jr. is resigning his seat to challenge County Executive Parris N. Glendening. Two other Democrats, Arthur B. Haynes and Artie L. Polk, are also in the race. There is no Republican primary.

Frank P. Casula is the only person on the council who doesn't face a primary challenge. Wilson's open seat on the County Council has attracted four Democratic hopefuls. In the 3rd District, Anne MacKinnon is a recently-minted incumbent, having joined the council this summer after the resignation of James Herl. She has drawn four challengers in the Democratic primary. And in the 2nd District, incumbent Anthony J. Cicoria, facing trial on charges of theft and tax evasion, has three challengers in the Democratic primary: Stephen J. Del Giudice, Margaret S. Mallino and Doyle Niemann.

There is only one school board primary, the 8th District seat being vacated by Angelo I. Castelli. The nonpartisan race includes James M. Davis, Anthony R. Dean and Frederick C. Hutchinson.

There are also primaries for sheriff, Circuit Court clerk and judge of Orphans' Court.