CHARLESTON, W.Va. -- Presumed Republican presidential nominee Mitt Romney is hoping for an endorsement from his party's West Virginia primary voters, who must also select 28 delegates to August's national convention in Tampa.

President Barack Obama tops the state's Democratic ballot in his quest for a second term. The primary also features congressional incumbents who are either unopposed or face poorly funded opponents.

U.S. Senate Joe Manchin faces a challenge in the Democratic primary from Sheirl Fletcher, a former Republican and ex-legislator. Unopposed on the GOP side is John Raese, who lost to Manchin in the 2010 special election that followed the death of Robert C. Byrd. The seat is now up for a full six-year term.

U.S. Rep. Shelley Moore Capito has two opponents, state Delegate Jonathan Miller and Michael Davis, in the GOP primary for the 2nd Congressional District. Howard Swint, William McCann and Dugald Brown are running for the district's Democratic nomination.

Republicans in the 3rd District must choose among Delegate Rick Snuffer, Lee Bias and Bill Lester as the challenger to Democratic Rep. Nick Rahall. Both Rahall and 1st District freshman Rep. David McKinley, a Republican, are unopposed today. Democrat Sue Thorn is similarly assured her party's nod as she seeks to take on McKinley.

The GOP national convention delegates include three from each congressional district and 19 at-large. More than 190 Republicans filed for these slots.

Secretary of State Natalie Tennant said more than 61,400 voters have already cast early in-person or absentee ballots, down from the 2008 primary by about 10,000 votes.