Senate Minority Leader Mitch McConnellAddison (Mitch) Mitchell McConnellMcConnell in talks with Mnuchin on next phase of coronavirus relief Pelosi: 'We shouldn't even be thinking' about reopening schools without federal aid The Hill's Morning Report - Presented by Argentum - All eyes on Florida as daily COVID-19 cases hit 15K MORE (R-Ky.) said he would support who ever wins the Republican Tuesday between O'Donnell and Rep. Mike Castle (R-Del.).

"The voters of Delaware are going to decide this very day as we are speaking who they want to represent them in the Senate," McConnell said during an appearance on MSNBC. "I'm going to support the nominee."

Castle is facing a last-minute conservative surge from O'Donnell, the Tea Party candidate who's been backed by former Alaska Gov. Sarah Palin (R) and Sen. Jim DeMint (R-S.C.) and his Senate Conservatives Fund.

O'Donnell is the latest insurgent Republican candidate backed by the Tea Party movement to threaten an establishment candidate, following Sharron Angle in Nevada, Mike LeeMichael (Mike) Shumway LeeKoch-backed group urges Senate to oppose 'bailouts' of states in new ads Gianforte halts in-person campaigning after wife, running mate attend event with Guilfoyle Sunday shows preview: Lawmakers to address alarming spike in coronavirus cases MORE in Utah and Joe Miller in Alaska. 

The outsider candidates have brought new voters to the primaries and generated enthusiasm, but also may be weakening the Republican party's field of candidates for the general election. Castle argues O'Donnell would lose a general election in Delaware, and polls suggest he's correct. 

McConnell has made clear that he welcomes members of all ideological stripes to the Senate GOP conference, though the new crop of would-be conservative senators is seen as potentially less loyal to him as GOP leader.

"I'm going to support the Republican nominee for the Senate anywhere in America," he said.

That support extends to Alaska, McConnell said, where he said he supported Miller rather than Sen. Lisa MurkowskiLisa Ann MurkowskiSixth GOP senator unlikely to attend Republican convention Koch-backed group urges Senate to oppose 'bailouts' of states in new ads The Hill's Morning Report - Presented by Facebook - Trump backs another T stimulus, urges governors to reopen schools MORE (R), the member of the Senate GOP leadership team to lose in that state's primary.

"She knows I'm supporting Joe Miller," McConnell said. "We expect him to be the next senator from Alaska."