Donald Trump took steps to appropriate much of the Republican National Committee’s financial and political infrastructure for his presidential campaign Monday, amid signs that he and the party would lag dangerously behind the Democrats in raising money for the general election.

Trump, who by the end of March had spent around $40 million of his fortune on the primaries, has said he may need as much as $1.5 billion for the fall campaign, but he will seek to raise it from donors rather than continue to self-finance.

But Trump has no fundraising apparatus to resort to, no network of prolific bundlers to call upon, and little known experience with the type of marathon, one-on-one serial salesmanship and solicitousness that raising so much money is likely to require — even if individuals can contribute up to the current limit of $334,000 at a time to the party. And he has to do it all in six months, with a deeply divided party that is still absorbing the fact that Trump is its standard-bearer.

“No one should underestimate how hard it would be for any nominee to raise hundreds of millions of dollars in a very short period of time,” said Mike DuHaime, who was the top strategist for presidential campaign of Gov. Chris Christie of New Jersey.

While Trump’s continued feud with the Republican establishment was likely to cheer his supporters, his intense need for money to run his general election campaign suggests the degree to which he will rely heavily on the party’s infrastructure.

Underscoring the urgency with which Trump and Republicans will need to increase their fundraising, some of the party’s allies who spent enormous sums in the 2012 election now appear likely to stay on the sidelines in the presidential race — including the vast Koch brothers network, which had pledged to spend nearly $900 million in 2016.

Mark Holden, chairman of the Freedom Partners Chamber of Commerce, one of the Koch network’s main umbrella groups, signaled that it would require a significant change in tactics by Trump, the presumptive Republican nominee, for his group to open the spigot.

“If during the general election cycle, a candidate were able to garner support from the public with a positive message in support of the issues we care about, and did not engage in personal attacks and mudslinging, we would consider potentially getting involved,” Holden said. “That hasn’t happened yet, and there is no indication that this will happen given the current tone and tenor of the various campaigns.”

The Karl Rove-led group American Crossroads is also in a wait-and-see crouch, with officials saying they have no immediate plans to buttress the Republican nominee. Both it and the Kochs’ network are now expected to focus more on aiding Republicans’ efforts to retain their majority in the Senate.

Republican Party officials have pressed Trump to sign a joint fundraising agreement, which would allow him to raise money for the national committee and for his own campaign simultaneously. That, in turn, would also give Trump a defensible answer for why, after months of railing against Wall Street executives and special interests, he recently turned to a former Goldman Sachs executive, Steven Mnuchin, to corral large checks for his campaign.

Both Trump’s aides and party officials were caught by surprise by the abrupt end of the primary contest last week, when Trump carried Indiana, prompting Sen. Ted Cruz of Texas and Gov. John Kasich of Ohio to withdraw from the race. But the two sides have hurried to wrap up a joint fundraising agreement, and one is close to being signed, according to people close to the national committee who were not authorized to speak publicly.

“As soon as there’s unity, it’s going to be very easy to do,” Trump said in an interview Monday, adding that he still planned to write checks for his campaign. “I think we’ll raise $1 billion,” he said.

Under a joint fundraising agreement, Trump and the party would most likely be able to raise even more than $334,000. But such efforts are difficult and take time: When the limits were lower in 2012, Mitt Romney raised less than $500 million under such an agreement that year,

using a donor network that had taken years to develop.

In one sign of progress for Trump, Stanley Hubbard, a billionaire broadcasting executive who had donated money to efforts to thwart him, fell in line behind him. “All my other candidates withdrew, one by one,” Hubbard said in an interview. “He was the last man standing.”

But other donors remain staunchly opposed. Paul Singer, the billionaire financier who had backed Sen. Marco Rubio of Florida, made clear at a gala Monday night for the Manhattan Institute, a conservative think tank, that he could not support Trump and was dismayed by the likely choices in the general election.

In a 3 1/2-hour meeting Monday at Republican headquarters in Washington, party officials detailed for Trump’s top aides the range of fundraising operations and the other political assets at his campaign’s disposal. These include the party’s trove of data on voters nationwide, the hundreds of organizers it has working across the country, and the dozens of employees in the party’s communications shop.

Trump chose not to assemble those kinds of extensive operations during the primary season, when he prided himself on winning contests on a shoestring and ran a skeletal operation compared with many of his rivals. So he may have to lean on the Republican National Committee in a way that few nominees have in recent years.

In the lengthy meeting, Trump aides and party officials tried to forge a path forward in tandem, with Republican officials delivering the less-than-subtle message that Trump’s aides were in little position to try a takeover of the group, according to a person briefed on the discussions.

“We can both learn a lot from each other because we both have the same objective — to defeat the Democrats in November,” Corey Lewandowski, Trump’s campaign manager, said after the meeting.