This time, Donald J. Trump says, he really means it.

The billionaire real-estate mogul, who has long amounted to a one-man sideshow in GOP presidential politics, said in an interview Wednesday that he is “more serious” than ever about pursuing a run for the White House in 2016.

In recent days, Trump said, he has hired staffers in key primary states, retained an election attorney and delayed signing on for another season as host of NBC’s “The Celebrity Apprentice” because of his political projects.

“Everybody feels I’m doing this just to have fun or because it’s good for the brand,” Trump said in an interview with The Washington Post. “Well, it’s not fun. I’m not doing this for enjoyment. I’m doing this because the country is in serious trouble.”

The moves are the most significant steps yet by Trump, 68, toward a bona fide presidential bid, which he considered briefly and flamboyantly in 2011 before deciding against a run.

The looming question, however, is whether he can convince Republicans that he is more than a celebrity bomb-thrower and instead is sincere in his consideration of a campaign. Trump is slated to appear ahead of former Florida governor Jeb Bush on Friday at the Conservative Political Action Conference, an annual gathering of conservatives near Washington.

Trump in recent years has served largely as a provocateur on the sidelines of Republican politics, flirting with “birtherism” and making other remarks casting doubt on President Obama’s credentials and love of country. GOP presidential nominee Mitt Romney frequently shared the stage with Trump in often awkward appearances during the 2012 campaign, providing ample fodder for Democratic attack ads.

Trump would face steep challenges entering a field that is almost certain to include Bush and Wisconsin Gov. Scott Walker, among a dozen others, including many conservative hopefuls who have built their own networks. But his entry would also bring into the race a colorful contender with deep pockets and a national following — attracting media attention and forcing others to respond to his views.

Democrats reacted to Trump’s plans with eye-rolling. “You mean there’s a chance that he could blow up the entire Republican field and get ‘Celebrity Apprentice’ off my television? Sign me up!” wrote Mo Elleithee, a spokesman for the Democratic National Committee, in an e-mail.

Many Republicans were also skeptical.

“It’s a free country and he can do whatever he wants with his money, but the notion of him being elected president is pretty remote,” said Thomas D. Rath, a former attorney general in New Hampshire. “Running for president shouldn’t be a reality show that you watch once a week.”

As part of his preparations, Trump met Monday in New York with Reince Priebus, the chairman of the Republican National Committee, telling him that he was actively mulling a presidential run, according to people familiar with the conversation. Priebus, who will remain neutral in the 2016 primaries, took the meeting because of Trump’s status as a prominent donor to the RNC.

For the moment, Trump’s consultants will be employed by his personal office, but they are likely to transition over to a new political group in the coming weeks. Donald F. McGahn, a partner at Jones Day, is counseling the businessman as he takes further steps.

Corey R. Lewandowski, a former director of voter registration at Americans for Prosperity, a group backed by conservative industrialists Charles and David Koch, has been asked by Trump to serve as his senior political adviser and manager for the campaign-in-waiting. Alan Cobb, a former political adviser at Koch Industries, is another Republican who has signed on with Trump and is assisting with recruitment.

Based in New Hampshire, Lewandowski will direct Trump’s efforts in the first presidential primary and nationally if Trump jumps into the race later this year.

“The dysfunction of Washington and politics as usual drew me away from other candidates and toward someone who’s gotten something done in the business world,” Lewandowski said in an interview. To doubters, he added: “Wait and see. Mr. Trump is going to reintroduce himself to the American public. This is going to be a real contest, and no one wants to see a coronation.”

Chuck Laudner, who advised former senator Rick Santorum’s 2012 victory in the Iowa presidential caucuses, will lead Trump’s expected campaign there. Laudner’s hire was first reported Tuesday by the conservative Breitbart news Web site.

And in South Carolina, Ed McMullen, who has assisted the presidential campaigns of Sen. John McCain (R-Ariz.), has agreed to serve as Trump’s state chairman and political adviser. Also on board is state Rep. James H. Merrill.

Advising Trump on communications is Sam Nunberg, a political operative who is an associate of Roger Stone, the famed New York-based GOP opposition researcher.

In the meantime, political insiders will be monitoring his words and movements closely to ascertain whether Trump is actually inching closer to a national run — an idea he has considered for nearly three decades, going back to the run-up to the 1988 Republican presidential primaries.

When Trump played with the idea of running in 2011, he went to New Hampshire to stoke speculation and issued similar statements about the “serious” nature of his exploration before bowing out and renegotiating his contract with NBC.

On Sunday, Trump, worth $4 billion on the Forbes billionaire list, visited Charleston, S.C., for a speech at the Citadel. While he was there, he met with Sen. Tim Scott (R-S.C.), a rising political player in the early primary state.

Last month, Trump was in Des Moines for a conservative summit hosted by Rep. Steve King (R-Iowa), where he made headlines by bashing both Romney and Jeb Bush. “The last thing we need is another Bush,” Trump said.

Laudner, who was also being courted by Santorum (Pa.) and Gov. Bobby Jindal (La.), said he signed on after driving through the state with Trump during that visit. During their conversations, Laudner said he became convinced that Trump was not leading him on.

In March, Trump will travel to Iowa once again for an agriculture summit and also to New Hampshire.

“I am more serious about this than I’ve ever been before,” Trump said in the interview. “I made the deal with Chuck and Corey and some more we’ll be announcing soon because I’m serious and I want to focus on making America great again. I don’t need to be out there raising money.”

On the television front, Trump said he is keeping his options open and holding off on confirming his role as host on another season of “The Celebrity Apprentice,” which NBC renewed earlier this month for a 15th season.

Nunberg said while Trump is open to doing the show, he has told NBC he cannot commit to hosting it.

Trump said his pitch is straightforward and meant to reach voters who are fed up with the political system, mixing conservative populism and a blunt message about leadership.

“People around the world are laughing at us,” he said. “Look at China, they’re killing us, taking our jobs. We have weakness in the Middle East and with ISIS. We have incompetent people running the country and I’m tired of it.”