More than 80 percent of Republicans who cast ballots in Wisconsin's presidential primary say they expect Mitt Romney to be the party's nominee.

Preliminary results of an exit poll in Wisconsin on Tuesday show Republicans divided on which candidate they trust most to handle health care.

The Wisconsin primary is the latest battleground for Romney and Rick Santorum in their race for the Republican nomination for president. Voters were also going to the polls in Maryland and the District of Columbia.

About 4 in 10 GOP voters in the Wisconsin and Maryland primaries say the most important trait a candidate can have is the ability to defeat President Barack Obama in November. Almost as many combined say that it's vital for a candidate to be a true conservative or have strong moral character. About 1 in 5 called it most important for a candidate to have the right experience.

The economy was cited as the top issue by a majority of voters in both states _ 6 in 10 in Wisconsin called it their most important issue as did just over half in Maryland _ and few say they see the economy on the upswing. Pluralities in both Maryland and Wisconsin say the economy is getting worse, while about a quarter in each state say it is improving.

The Supreme Court's hearing last week on the 2010 health care law brought that issue to the forefront of the nomination campaign. Rick Santorum criticized Romney's record on the issue and appeared outside the Supreme Court to make the case that he is the candidate best suited to handle health care.

Wisconsin voters were split between Romney and Santorum as most trusted to manage health care policy, with about a third choosing each. About 1 in 6 say they trust Ron Paul most on the matter, 1 in 10 prefer Newt Gingrich.

Voters in the two states are among the least conservative to cast ballots this primary season. Just three states have had fewer voters calling themselves "very conservative."

About a third of GOP voters in each state said they were born-again or evangelical Christians.

In Wisconsin, Republican Gov. Scott Walker earns an 82 percent approval rating from GOP primary voters. Walker will face a recall election in June.

Exit polls in Maryland and Wisconsin were conducted for The Associated Press and the television networks by Edison Research. This includes preliminary results among 735 Republican voters interviewed Tuesday as they left their polling places at 25 randomly selected sites in Maryland, and among 1,063 Wisconsin GOP voters as they left 35 polling places across the state. Results from Maryland have a margin of sampling error of plus or minus 5 percentage points; it is 4 points for the Wisconsin survey.