Carson said he supports Manchin, but it would be difficult to repeat Byrd's accomplishments.
Downtown Martinsburg business owner Melissa Faircloth said she is "not impressed" with Manchin.
If Capito decided to run, Faircloth said the congresswoman would "have my vote" because of her stance on Christian principles.
"I just think we have a lot the same values," Faircloth said.
Barbara Bradley, a member of Main Street Martinsburg, said she wasn't surprised by Manchin's candidacy.
Bradley said she too would back Capito if she decided to run for Senate.
"I love Shelley ... She's a strong Republican woman," Bradley said.
At War Memorial Park, Carl Odell of Charles Town, W.Va., said Manchin made a good decision to run.
"I think he's made a fine governor and I think he'll make a fine senator," Odell said.
As governor, Manchin helped improve education and the state's economy, Odell said.
"He keeps things on an even keel," Odell said. "I really like what he's done. I think he's a good man."
Berkeley County Republican leader Mick Staton said he believes Manchin is a "very formidable candidate."
"We want to outdo the Massachusetts miracle," Staton said of that state's surprise election of Republican Scott Brown earlier this year. Brown is serving the unexpired term of the late U.S. Sen. Ted Kennedy, D-Mass., who was regarded as the Senate's liberal lion.
Staton said that most people in West Virginia can't remember having a Republican senator, noting that the last to serve was W. Chapman Revercomb, who lost to Byrd in the 1958 general election.
"We think we have a great shot," said Staton, who chairs the Berkeley County Republican Executive Committee.
If Capito were to run for the Senate seat, Staton said he expects she would at least carry the Eastern Panhandle counties.
"She's a very familiar face," Staton said.
Even if she doesn't run, Staton said a strong GOP candidate will make it tough for Manchin to win in Berkeley County, which was one of only three counties to vote against Manchin in his first bid for governor in 2004.
Staton said he expects more than one Democrat to run for the seat and possibly even more candidates in the Republican race.
"These chances don't come along very often," Staton said.
Jefferson County native Rod Snyder, who was elected the 39th president of the Young Democrats of America organization on Sunday, predicted it will be difficult for any Republican who challenges Manchin.
"I think that he is by far the front runner in this race," Snyder said. "The Democratic Party is very excited to support him."