DES MOINES, Iowa — Florida Gov. Ron DeSantis and former United Nations Ambassador Nikki Haley are increasingly outsourcing central parts of their campaigns, drawing on the growing urgency of Donald Trump opponents to find a single alternative to the former president.

Struggling to energize his campaign, DeSantis this week privately encouraged his donor network to support a newly formed super PAC that’s taking over advertising responsibilities. That was after a leadership shake-up at the pro-DeSantis super PAC that for months has been handling most of his advertising and get-out-the-vote operations.

At the same time, Haley’s self-described “scrappy” political campaign, which has never enjoyed the same level of funding or personnel as DeSantis’ operation, won the support of the Koch network, the largest conservative grassroots organization in the nation. By week’s end, scores of Koch-backed activists were expected to begin advocating on Haley’s behalf at the doorsteps of tens of thousands of Republican primary voters.

The extraordinary reliance on independent groups for the two Republicans who increasingly appear to be Trump’s closest challengers is testing the practical and legal limits of modern-day presidential campaigns. And with less than two months before the Iowa caucuses, neither candidate has shown the ability to disrupt Trump, the front-runner for another presidential nomination.

DeSantis has relied on outside support perhaps more than any major candidate since the U.S. Supreme Court in 2010 paved the way for super PACs, which are committees that can raise unlimited amounts of money without having to disclose their donors. Federal law prohibits candidates and their formal campaigns from coordinating directly with super PACs.

DeSantis publicly committed to visiting all of Iowa’s 99 counties, a traditional measure of commitment to the first state in the GOP calendar.

Never Back Down, the original super PAC supporting him, followed suit. While DeSantis will visit Jasper County — his 99th — with a campaign event Saturday, Never Back Down has chauffeured him to 92 of the other counties, according to the super PAC’s schedule.

During the first week of August, DeSantis traveled to more than a dozen Iowa counties on the bus chartered by Never Back Down with the super PAC’s top tactician, David Polyansky, on board.

On Aug. 8, the DeSantis campaign announced a staff shake-up, replacing its campaign manager and hiring Polyansky from the super PAC to serve as deputy campaign manager. Polyansky is an Iowa campaign veteran. DeSantis spokesman Andrew Romeo said it was “totally false” to assert that DeSantis coordinated any campaign strategy with the super PAC.

In the memo to donors this week, DeSantis’ campaign manager James Uthmeier promoted both Never Back Down and a new pro-DeSantis super PAC, Fight Right, noting that 100% of Fight Right’s proceeds would be spent on television advertising.

“As Donald Trump and Nikki Haley work side-by-side spending tens of millions of dollars to attack Ron DeSantis, Fight Right’s emergence provides welcomed air support,” Uthmeier wrote in the memo obtained by The Associated Press. “In the final push for the Iowa Caucus victory, this campaign will proudly fight alongside NBD’s impressive ground game, and Fight Right’s television team, to show the people of Iowa that this is a time for choosing, and Ron DeSantis is the candidate that can WIN!”

Such language may not technically violate campaign finance laws that prevent direct coordination, but they may violate their common sense interpretation, said Shanna Ports, an attorney with the Campaign Legal Center, a Washington- based nonpartisan watchdog group. “When we see this kind of activity, there are some alarm bells that go off,” Ports said. “This does blur the lines between the campaign and the super PACs, particularly when you see super PACs taking on traditional campaign functions.”

Haley, too, is leaning heavily on outside groups to run traditional campaign functions — particularly her door-to-door canvassing, which is critical in Iowa and New Hampshire.

Haley’s team privately acknowledges that it needs help on the ground in early primary states, where DeSantis and Trump have much larger operations. It also remains unclear whether she has the funding to challenge Trump or DeSantis should the nomination fight go deep into the spring.

The Koch network’s support could fill in some of the campaign’s gaps.

Just days after their endorsement, the Kochs have already begun initial conversations with the pro-Haley super PAC known as the SFA Fund on how best to coordinate their efforts. While campaigns and outside groups cannot coordinate legally, outside groups can coordinate among each other.

Americans for Prosperity, the Kochs’ political arm, has 10 full-time staffers in Iowa and a much larger network of volunteers, according to state director Drew Klein.