City officials in Las Vegas and Cincinnati have withdrawn their bids to host the 2016 Republican National Convention, just weeks before the party’s site selection committee is set to begin visiting possible host cities.

Meanwhile, party officials said the RNC’s site selection committee voted Thursday to move bids by Kansas City and Dallas on to the next round.

The Las Vegas and Cincinnati host committees had been aggressively courting members of the site selection panel and were among six finalist cities. But organizers in both cities were uncertain that an arena big enough to house the tens of thousands of delegates, alternates and guests would be available, according to an RNC official. Both cities were also worried they could not meet the RNC’s criteria for onsite preparation time.

“We unwaveringly believe that Las Vegas offers the most compelling business, logistical and quality of experience reasons to be selected as the venue for a national political convention,” Nev. Lieutenant Gov. Brian Krolicki wrote in a letter to the site selection committee chairman, “but the members of the Las Vegas 2016 Host Committee respectfully defer to the determination of your Site Selection Committee and to the guidance from the RNC strictly adhering to these mandatory conditions.” He said the city would defer its bid to 2020.

Nevada political analyst Jon Ralston said the Las Vegas host committee was also unsure it could raise the money required to host a convention, a tab that would have run into the tens of millions of dollars.

Two Republican officials with knowledge of the process confirmed to The Washington Post that Las Vegas and Cincinnati had dropped their bids.

Money could be an issue for other cities, as well. In March, Congress moved to redirect funding for national political conventions to pediatric medical research, meaning host committees could be forced to raise tens of millions of extra dollars for security and other purposes.