She announced her decision Monday.
Capito, 51, was pressured by national GOP officials to challenge 87-year-old Byrd, a Democrat, who has been an outspoken critic of President Bush and the war in Iraq.
Capito did not entirely eliminate the possibility of taking on Byrd, noting that candidates have until January to file the necessary paperwork.
"But my intent is to run for my seat again and then see what the future brings," she said.
Her decision, she said, was one in which she is comfortable and which brought relief.
"I'm relieved in a lot of ways because there'd be a lot of money raising," she said. "I was worried about outside groups coming in like we saw in 2004. That's a source of concern for me."
Capito said she believes she can make a difference in the House, where she is a member of the Rules Committee.
"We've set economic policies that are going well. There's lots of work that still needs to be done and I'm just kind of growing my ... not so much my influence, but my ability to read my constituency and move towards policy," she said.
Along with the potential for a tumultuous campaign, Capito said other factors also influenced her decision.
"I thought about a lot of things. Basically what would be the best for West Virginians - where do they want me right now," Capito said.
She said she has spent the last month or so traveling around the state to "test the waters."
She said she found people felt she was doing a good job and wanted her to seek a fourth two-year term in the House.
Along with visiting the school Wednesday, Capito toured Essroc, a cement manufacturing plant outside of Martinsburg, and presented the Berkeley County Emergency Ambulance Authority with a grant from the U.S. Department of Homeland Security.
To the Rosemont Elementary School students she read the books "Piggie Pie!" by Margie Palatini and "There Was an Old Lady Who Swallowed a Bat!" by Lucille Colandro.
Afterward, Capito asked the students whether they all know what costumes they plan to wear for Halloween.
She interrupted an unintelligible slew of responses to ask, "Is anybody going to be a congresswoman?"
The 19 students listened but then continued to loudly state their choices, none of which sounded as if they plan to be a congresswoman.