Adelson's endorsement -- a powerful call for Republican unity -- followed Trump's visit to Washington on Thursday where he worked to smooth relations with top congressional Republicans.
"You may not like Trump's style or what he says on Twitter, but this country needs strong executive leadership more today than at almost any point in its history," Adelson wrote
in The Washington Post. "I am endorsing Trump's bid for president and strongly encourage my fellow Republicans — especially our Republican elected officials, party loyalists and operatives, and those who provide important financial backing — to do the same."
Adelson's op-ed did not detail how much he will spend to boost the GOP nominee.
Adelson's backing "an incredible honor" coming from "a person I have such tremendous respect for."
House chairmen back Trump
Trump's campaign on Friday also touted the support of nine House committee chairmen who have endorsed the presumptive GOP nominee in the last two weeks.
The chairmen of the Small Business, Agriculture, Financial Services, House Administration, Veterans' Affairs, Budget, Rules, Transportation and Science committees released a joint statement through the campaign Friday expressing their support for Trump, calling it "paramount that we coalesce around the Republican nominee" to maintain Republican control of Congress.
All nine chairmen -- Reps. Steve Chabot (Small Business), Michael Conaway (Agriculture), Jeb Hensarling (Financial Services), Candice Miller (House Administration), Jeff Miller (Veterans' Affairs), Tom Price (Budget), Pete Sessions (Rules), Bill Shuster (Transportation and Infrastructure), and Lamar Smith (Science, Space and Technology) -- had already committed to supporting Trump in the last two weeks.
"There is a path to winning in November, and it comes through unity. To solidify this partnership, we endorse Mr. Trump as the Republican nominee for President and call upon all Americans to support him," the chairmen said in the campaign's statement.
Trump met Thursday with House Speaker Paul Ryan, RNC Chairman Reince Priebus and House and Senate Republican leaders, aiming to forge unity after a divisive primary and amid ongoing questions about Trump's conservative credentials.
Both Trump and Ryan said the meeting was productive and suggested the pair were headed in the right direction toward uniting as a party, one week after Trump became the party's presumptive nominee and Ryan said he was not yet prepared to support him.