Limbaugh is a strong critic of John McCain.

(CNN) — Calling it his "non-concession speech," talk-radio host Rush Limbaugh launched a fresh round of attacks Wednesday on newly-minted GOP frontrunner John McCain — the latest indication the Arizona senator is likely to witness a backlash from some conservative quarters as he seeks to wrap up his party's nomination.

Limbaugh, a longtime conservative critic of McCain, said the senator's rise is largely the result of "uninspiring" candidates, and a "fractured" party base.

"There was no figure in our roster of candidates who rose up to challenge him or galvanize conservative support," Limbaugh said on his daily radio program. "All the candidates on our side, for various reasons, are uninspiring or worse — and so, just as I predicted, the base has fractured."

McCain has long had trouble courting the most conservative members of his party — and exit polls from the early-primary states have shown the Arizona Republican has consistently lost among those primary voters who identify themselves as conservative.

McCain passed a key test Tuesday in winning Florida's primary — the first early contest that closed out Independents and cross-over Democrats — but exit polls out of the state show he still lost the conservative vote to Mitt Romney.

"He is not the choice of conservatives, as opposed to the choice of the Republican establishment — and that distinction is key," Limbaugh continued. "The Republican establishment, which has long sought to rid the party of conservative influence since Reagan, is feeling a victory today as well as our friends in the media. But both are just far-fetched and wrong.”

– CNN Producer Alexander Mooney