Aside from Donald Trump himself, casino billionaire Sheldon Adelson may be the most sought-after man in Cleveland this week.

Republicans seeking to help finance Trump’s presidential bid have been eager to see if Adelson will give Trump the kind of enormous donation that has become a trademark of past election cycles. He gave close to $100 million in 2012, according to one analysis, and The New York Times reported in May that Adelson was poised to do the same for Trump.

Organizers of two so-called super PACs, which are legally allowed to raise and spend unlimited amounts to support a presidential candidate, told ABC News they are “desperate” to attract large-dollar donors like Adelson while in Cleveland, now that Trump seems to have moved beyond the assertion that he would self-finance his entire campaign.

“I would love to have more money, if you know somebody who wants to give it we’ll take it right now,” said Ken McKay, who heads the Rebuilding America Now PAC. “We need the money desperately.”

McKay said emissaries from his group have met with Adelson in Cleveland. Known in fundraising circles as a “whale” because of his ability and willingness to give so much, Adelson has been pursued all week.

The casino magnate has been a conspicuous presence, moving in and out of his Ritz Carlton hotel suite with a large security contingent. When ABC News approached him to ask about his plans for 2016, security guards brushed reporters aside and put their hands up to block cameras. Calls to his spokesperson were not returned.

The need for support from such mega donors stem largely from the weak position Trump supporters find themselves in just four months to election day. A new ABC News analysis of data from CMAG/Kantar Media, which tracks advertising spending, shows Hillary Clinton and the main super PAC that supports her have spent a combined $152 million on television ads. Most have appeared in key swing states where the presidential contest could rise or fall.

Trump has not spent any money on television ads. The groups supporting his bid have spent a total of $4.9 million.

Those organizing Trump’s fundraising push told ABC News they are trying to step up their efforts. Among those vying to take the lead in the effort are Great America PAC and Rebuilding America Now PAC.

“We think that everybody’s really going to come together this week at the convention,” said Eric Beach, who is overseeing the Great America PAC. “When we leave from Cleveland this week, there’s going to be a clear directive on how we achieve victory in November.”

They acknowledged they had a late start and worry most about the lack of organization for Election Day efforts to mobilize voters. Campaign experts said the advertising deficit has not hurt Trump as much as it would a traditional candidate.

“The Trump campaign has not needed to raise as much money as one would have expected to be viable at this point in the campaign, and that’s almost exclusively because he brings celebrity — He brings this shock-jock approach to politics, which the cameras cannot resist,” said Sheila Krumholz, Executive Director of the Center for Responsive Politics.

Krumholz said the weakening of campaign finance restrictions has made it possible for candidates to raise the money they need from fewer donors. Much of that money can come in unlimited quantities and be given with little disclosure.

“The impact of secrecy in politics is that people cannot know who’s behind the messages that they’re being bombarded with,” Krumholz said.

In Cleveland, all indications have been that participation in fundraising events has been slower than expected. Several major corporate sponsors of the convention itself backed out before it began. A number of receptions were either canceled or ended early because the expected crowds never materialized.

But McKay said he remains optimistic. At a meeting with donors Wednesday, he said Trump campaign manager Paul Manafort called in and “spoke on our behalf, to the extent legally possible,” McKay said.

McKay said he hopes that is just “the kind of signal that people like Mr. Adelson need to see.”

(AP)