Shank spends time on committee work and individual bills, often in criminal justice. In recent years, he also has been a voice of the Republican minority, often criticizing Gov. Martin O'Malley and other Democrats.
Munson was a delegate from 1975 to 1991 and is finishing his fifth term as a senator.
Shank is nearing the end of his third term as Subdistrict 2B's delegate.
Both ran unopposed in 2006.
The winner of Tuesday's primary won't have any Democratic opposition in the Nov. 2 general election.
During a visit to Washington County this summer, former Gov. Robert Ehrlich -- whom Munson and Shank both support -- laid out their differences.
In praising both but endorsing neither, Ehrlich said: "... Don has his view concerning what the job should look like and it's more of an accommodation view, if you will, with (Senate President) Mike Miller and the Democrats. Chris has a more aggressive view concerning standing firm on some principles and establishing that comparison and contrast between what he views where the Republicans should be as opposed to Mike Miller and the Democrats."
Shank's campaign mailings have attacked Munson for voting for increased state spending over the years and "advancing the Democrats' liberal social agenda."
But Munson said voting against the budget hurts a legislator's constituents. He said he makes the most of his Budget and Taxation Committee position each year -- cutting what he can, then ensuring Washington County gets its share.
"It's their tax money," he said. "It's just a matter of bringing it back here."
Among the county's state lawmakers, Munson most consistently goes after bond-bill money to help local organizations.
Shank, though, said legislators need to direct their attention toward reducing spending. During the last session, he and the House Republican Caucus proposed hundreds of millions in cuts that were rejected by the Democratic majority.
He said he made a promise in 1998, during his winning campaign for state delegate, to fight large government, big spending and high taxes.
"Unchecked government spending has led to crippling taxes," hurting the state's ability to attract new businesses, Shank said.
Munson has said he also opposes tax increases, but has voted for two -- a new income tax on millionaires and a doubling of the state's cigarette tax. In both cases, Munson offered his vote in exchange for results that helped the University System of Maryland at Hagerstown campus.
One of the most highlighted votes in this primary campaign has been Munson's support of $1 million for a multicultural center for Casa de Maryland, an advocacy group for Latinos and immigrants. Critics say the group helps illegal immigrants.
Shank has pointed to that vote as an example of Munson's liberal ways.
After a few different explanations, Munson has said the vote was a mistake -- he pushed the wrong button and didn't realize until it was too late to change it.
Munson said he and Shank both oppose and want to curtail illegal immigration. Most people realize immigration is largely a federal issue and Shank is only harping on it because he has little else of substance to bring up, Munson said.