Robert F. Kennedy Jr.’s decision to suspend his presidential campaign and endorse former President Donald J. Trump was — depending on where on the political spectrum the coverage came from — treated with either outright glee — or derision. Conservative sites primarily focused on the potential electoral boon to Mr. Trump, while liberal media outlets focused more on Mr. Kennedy’s dysfunctional campaign, including by returning to several negative story lines.

Mr. Kennedy announced on Friday that he would suspend his presidential campaign in key battleground states, though he intended to remain on the ballot in some states. He suggested he worried his presence in the race would pull voters away from other candidates, though recent polling wasn’t clear about who might benefit from Mr. Kennedy’s change in plans.

Conservative sites, more than a dozen of which prominently featured the news on their home pages, saw the news as a win for Mr. Trump. They argued that Mr. Kennedy’s decision could reshape the race by turning Mr. Kennedy’s supporters into Mr. Trump’s, and by shifting the attention of Americans away from this week’s Democratic National Convention.

Liberal media outlets described Mr. Kennedy’s decision as self-serving, and in keeping with his unpredictable campaign. Several referenced Mr. Kennedy’s assertion that Mr. Trump had offered him a role in a second Trump administration, something the former president declined to confirm on Friday. The sites referred to him using words like “power-hungry” and “transactional.”

Here’s how the news was covered by a selection of outlets:

FROM THE RIGHT

The Washington Examiner

Though polling suggests Mr. Kennedy’s decision is unlikely to significantly shift the race between Vice President Kamala Harris and Mr. Trump, many conservative commentators said the decision could swing the contest. Ben Shapiro, the editor in chief of The Daily Wire, said in a livestream after Mr. Kennedy suspended his campaign that the announcement, which was made during a speech in Phoenix, could “dwarf” the positive impact of the Democratic National Convention for Ms. Harris.

The Washington Examiner, a conservative news site, published multiple news articles on Friday that argued an endorsement from Mr. Kennedy would boost Mr. Trump’s campaign.

Haisten Willis, the site’s White House reporter, wrote that the decision “eliminates the third-party threat to the G.O.P. and could push momentum back in Trump’s favor as polls show a tight race against Harris.”

In an opinion essay titled “R.F.K. Jr. and Trump Offer a Good Fit” published on the site on Friday, the writer Brady Leonard said that Mr. Kennedy’s endorsement offered an alliance that not only helped Mr. Trump’s odds in the election, but also made sense ideologically.

“Both value individual liberty far more than Vice President Kamala Harris, and both view the so-called deep state as the enemy and are skeptical of America’s interventionist foreign policy,” Mr. Leonard wrote.

FROM THE RIGHT

Breitbart

Breitbart, a conservative news site, plastered the news of Mr. Kennedy’s endorsement on its front page Friday afternoon, referring to it as a “MAGA/Independent Alliance” in all-caps and bright-red letters, and asserting that the “epic announcement” had upstaged the Democratic convention.

Mr. Kennedy ran “to shake Washington free from the grip of establishment elites,” wrote Joel Pollak, Breitbart’s senior editor at large, adding that “unlike many Democrats, he did not demonize Trump or Trump supporters.”

In another article, titled “R.F.K. Jr. Lays Out How the D.N.C. Dismantled Democracy,” Hannah Knudsen, a Breitbart reporter, focused on Mr. Kennedy’s comments on Friday about how Democrats tried keep him off the ballot in some states. Ms. Knudsen wrote that Mr. Kennedy highlighted that “Democrats essentially dismantled democracy while supposedly trying to save it.”

FROM THE LEFT

Slate

Liberal media outlets were less convinced that Mr. Kennedy’s announcement would markedly help Republicans in November. But they continued to characterize Mr. Kennedy unfavorably for even trying to help Mr. Trump.

Ben Mathis-Lilley, a senior writer for the liberal site Slate, said Mr. Kennedy’s campaign was ending “like the lives of the brain worms, allegedly barbecued dogs and bears found deceased on a roadside who have had the misfortune of crossing paths with him.”

The site had previously referred to supporters of his in Silicon Valley as his “Brain Worm Coalition,” in reference to Mr. Kennedy’s comments in May that he had a parasite in his head. One article called his running mate, the lawyer Nicole Shanahan, a “rich rando,” shorthand for a random person, and another said Mr. Kennedy appeared “more erratic than ever” last month in a piece summing a selection of his public appearances.

Referring to Mr. Kennedy as “unpredictable,” Mr. Mathis-Lilley questioned Mr. Trump’s strategy of bringing him on as a campaign surrogate.

“What’s to say that he won’t decide in a month that he needs to denounce Trump and re-enter the race?” Mr. Mathis-Lilley wrote.

Meidas Touch, a liberal news outlet, reacted to the news with an episode of its “Legal AF” podcast. On it, Michael Popok, a host, said that Mr. Kennedy’s campaign had been in free fall since he admitted to leaving the carcass of a bear cub in Central Park in 2014. He also referenced Mr. Kennedy’s assertion on Friday that Mr. Trump had offered him a role in a second Trump administration.

“He’ll sell himself to the highest bidder,” Mr. Popok said. “I thought Donald Trump was transactional. R.F.K. Jr. is worse, if that’s possible.”