When national Republicans convened for their winter meeting in Washington this past January, they were met by a well-oiled lobbying operation with all of the force and money of Las Vegas behind it.

The city, urged on by mega-donors including the billionaire casino magnate Sheldon Adelson, was jockeying to host the 2016 Republican National Convention, and the bid was aggressive.

At the Renaissance Hotel, a chic Las Vegas 2016 wi-fi lounge greeted meeting attendees, and a top-flight team of well-connected Republican operatives roamed the hallways, gauging enthusiasm for the bid and working to stoke interest.

Jackpot? Not quite.

The bid by Las Vegas to host the 2016 convention came to an official end Thursday when the city announced it would withdraw itself from consideration.

But the lobbying effort behind the bid, at its start highly sophisticated, had in fact been winding down for several months, increasingly crippled by mounting questions over fundraising, including the level of support from major benefactors such as Adelson. By the time Republicans converged on Memphis for their spring meeting earlier this month, the showing for Las Vegas was only a fraction of that from January.

In a letter to the Republican National Committee, Nevada Lt. Gov. Brian Krolicki, chairman of the Las Vegas 2016 Host Committee, wrote that the city withdrew its bid because it had "become clearly evident" that it would not be able to meet the requirements to host the convention, citing concerns over venue space and timing.

Those were indeed legitimate problems, sources close to the process confirmed -- in part due to back-channeling by allies to Senate Majority Leader Harry Reid, D-Nev., who will be up for re-election in 2016 and would not be helped by Republicans converging on his home state during the campaign.

"The host committee is a nonpartisan, nonpolitical organization, but I think there was some pressure privately" from Reid's allies, said one Republican involved in the bid.

There has been some speculation publicly that social conservatives also had a hand in derailing Vegas' bid to host the convention, fearing bad optics at best or, at worst, potential scandals. But Republicans intimately involved in boosting support for the bid said those concerns likely weren't to blame for killing the project.

There were, however, numerous other political and logistical wrinkles at play.

Central to Las Vegas' appeal was that, with prominent Republican donors such as casino magnates Steve Wynn and Adelson supporting the bid, it seemed all but certain that the host committee would be able to raise the money necessary to stage the convention.

But organizers might have leaned too heavily on Wynn, Adelson, and a handful of other Las Vegas mega-donors, who did not want to single-handedly fund the venture.

"That certainly wasn't going to happen," said one source familiar with the bid.

And for Adelson in particular, "what has happened in the intervening period is, there's now this internecine fight over Internet gaming," explained another Republican familiar with the Las Vegas bid.

A push to ban Internet gaming nationwide is, for Adelson, a top priority — and, as the issue began to consume more political oxygen, it proportionally deflated his focus on the convention bid, the Republican said.

A spokesperson for Adelson, Ron Reese, told the Washington Examiner that Adelson remained supportive of the Las Vegas 2016 bid throughout, but did not offer any further detail on the record.

Among the cities vying to host the 2016 Republican National Convention, none received more attention — positive and negative — than Las Vegas, which simultaneously excited and worried organizers and potential attendees.

The city could still host a Republican convention: In its withdrawal letter, the host committee indicated Las Vegas would vie for the honor in 2020.

For now, however, four cities remain in contention to host the 2016 convention: Kansas City, Denver, Cleveland and Dallas.