Sen. Mark R. Warner and Republican rival Ed Gillespie will square off Saturday in their first, and perhaps only, debate in a race that until now has stayed under the radar despite its two big-name candidates.

A quirk of event planning puts their 90-minute faceoff outside the state that each man seeks to represent in the U.S. Senate. They meet at the Greenbrier, a luxury resort just over the West Virginia line, where the Virginia Bar Association is hosting the event as part of its annual summer meeting.

Libertarian Party candidate Robert Sarvis, who took nearly 7 percent of the vote in the 2013 race for Virginia governor, qualified for the U.S. Senate ballot this year, but the bar association deemed him too much of a long shot to put him on stage with Warner (D), a former Virginia governor running for a second Senate term, and Gillespie, a former Republican National Committee chairman and GOP strategist. A Twitter campaign by Sarvis fans failed to persuade organizers to reconsider.

Moderated by Judy Woodruff, co-anchor of “PBS NewsHour,” the debate will not be televised but can be viewed via a NewsHour live stream and on the bar association’s Web site. It begins at 11 a.m.

So far it is the only debate that Warner and Gillespie have both agreed to hold. Gillespie has said yes to seven others, as might be expected of an underdog seeking to boost his visibility. Warner has not agreed to any other debates so far.

Republican Va. Senate hopeful Ed Gillespie. (Melina Mara/The Washington Post)

“We are assessing all invitations,” said Warner spokesman David Turner.

Warner has big advantages in campaign cash and name recognition over Gillespie, who has been active on the national stage for decades but has never held elective office. Warner has raised $14 million in the race and has $8.9 million in cash on hand, according to the most recent fundraising reports. Gillespie has pulled in $4.1 million, with $3.1 million of it still on hand.

A Roanoke College poll released this week shows Warner with a 25-point lead over Gillespie.

The Senate race has grabbed few headlines since Gillespie won the Republican nomination at a June nominating convention in Roanoke.

Barring any gaffes or surprising statements from either candidate, the debate is not expected to suddenly transform what has been a bit of a sleeper to the daily rock ’em, sock ’em of last year’s governor’s race. The 2013 contest between now-Gov. Terry McAuliffe (D) and then-attorney general Ken Cuccinelli II (R) was an intensely personal battle between rivals who both claimed the other was unfit for the job. McAuliffe portrayed Cuccinelli as right-wing zealot, while Cuccinelli characterized McAuliffe as a shady wheeler-dealer.

That has not been the tone of the Warner-Gillespie race, which for the next month or more is likely to be overshadowed by the federal corruption trial of former governor Robert F. McDonnell and his wife, Maureen. That gets underway Monday in Richmond.

Gillespie has primarily gone after Warner for supporting President Obama, most notably by voting for the federal health-care overhaul. The Democrat’s campaign has hit Gillespie for his opposition to raising the minimum wage.

Sen. Mark R. Warner (D-Va.) (Alex Wong/Getty Images)

“There will be digging into Gillespie’s past as a lobbyist, some argument about Warner’s business and political connections from 20 years ago. None of it is likely to be the dominant theme of the campaign, which is far more on issues here,” said Bob Holsworth, a longtime Virginia political observer.

Pete Snyder, a Northern Virginia technology entrepreneur who unsuccessfully sought the GOP nomination for lieutenant governor last year, would like to see it stay that way.

“So far on both sides, this is a race worthy of Virginia,” he said. “We’ve gotten so used to being in the gutter for so many years. It’s nice to return — hopefully, it won’t be briefly — to the Virginia way.”