MILWAUKEE - Donald Trump is running one-man race to finish with the 1,237 delegates needed to secure the first-ballot GOP presidential nomination, and many are speculating that Tuesday's primary in Indiana could put him well on track to meet his goal.

Trump's success is anything but a given, but polling numbers suggest he's ahead in Indiana and poised for a campaign-defining win there. A loss in Indiana will hinder his chances to get the delegates he needs, and if he falls short by the GOP convention, many speculate he may not get the nomination at all.

WTMJ conservative talk show host Charlie Sykes - and a host of other statewide radio personalities - took to the airwaves, online, in print and on television, posing as a huge thorn in the side of the GOP frontrunner in Wisconsin. Many have given credit to their daily inoculations of the "Party of Trump" for leading to his double-digit loss to rival Ted Cruz in Wisconsin. Whether you agree with his commentary or not, and whether you love him or hate him, Sykes' audience and reach in the state puts him out front of what the New York Times calls "The 6 Radio Hosts on a Mission to Stop Donald Trump in Wisconsin."

Sykes' criticism of Trump is nothing new. He has been a local leader of the #nevertrump movement, and has been consistently an outspoken critic of the candidate. George Will joins #NeverTrump: If Trump is nominated, the GOP must keep him out of the White House https://t.co/fFRIYSq2Nk

"I feel very strongly that Donald Trump poses a fundamental challenge to the conservative movement, an existential challenge, so, yes, I have made it my mission to stop him," Mr. Sykes told the New York Times in April.

#WIPrimary town map via @uselectionatlas. Cruz (yellow) Trump (orange) . @DecisionDeskHQ exit poll nailed this race. pic.twitter.com/wO1RAPH93K — J. Miles Coleman (@JMilesColeman) April 30, 2016 Above is a map showing how Wisconsin voted in the April primary election.