A Washington, D.C., fundraiser scheduled for this week for North Carolina House Speaker Thom Tillis, a Republican candidate for Senate, will feature a few big GOP names, including Senate Minority Leader Mitch McConnell.

Sens. Lindsey Graham, R-S.C., and Mike Enzi, R-Wyo., are also slated to attend, according to an updated invitation sent out Monday and obtained by the Washington Examiner.

Thursday's breakfast event will be at the home of Geoffrey Gray, a lobbyist who has represented Fannie Mae and Freddie Mac, among additional interests in banking, financial and other sectors. The event is $500 to $1,000 per head and up to $2,500 for political action committees.

McConnell's political action committee has donated to Tillis' campaign, but the appearance at the fundraiser of the Senate's top Republican is an important visible stamp of approval for Tillis' candidacy. McConnell's colleague, Sen. Rand Paul, R-Ky., endorsed another Republican in the North Carolina Senate primary, physician Greg Brannon. Still, Tillis, the favored candidate of the National Republican Senatorial Committee, holds a considerable fundraising advantage.

For Republicans, beating Sen. Kay Hagan, D-N.C., is a critical step toward retaking control of the Senate in 2014. Hagan has been polling neck-and-neck with Tillis, Brannon and Mark Harris, a Baptist pastor also seeking the Republican nomination.

Update: Brannon responded to the news of Tillis' fundraiser in a statement: "Senator McConnell's support of my opponent isn't surprising. He's heavily supported by the DC establishment that's declared war on the tea party and the conservative grassroots."