Committeeman John Ryder of Tennessee told CNN there is no likely scenario under which former Gov. Mitt Romney of Massachusetts won't be the party's nominee.
"I think a major focus of this meeting will be for people to start to come together behind the nominee and get ready for the contest in November," Ryder said.
Saul Anuzis, a national committee member from Michigan, said the "rallying point" for Republicans should be Gov. Romney's speech on Friday.
"This is an opportunity to bring the party behind Romney and pull everyone toward the general election," Anuzis said.
Sen. John McCain of Arizona will also address the GOP conference in an appearance that one member described as the "passing of the torch" from one Republican nominee to the next.
National party officials said former House Speaker Newt Gingrich and U.S. Rep. Ron Paul of Texas have both been invited to the meeting and will have representatives there.
Gingrich and Paul have not dropped out of the race but Romney's top rival, former Sen. Rick Santorum of Pennsylvania, departed earlier this month.
During the three-day meeting, state party leaders will be briefed on the RNC's national campaign machinery. New technology initiatives will be unveiled and fundraising will be discussed.
GOP pollster Frank Lunz will host a political briefing and there will be training sessions and numerous speeches before the meeting winds up.