NEW YORK (NYTIMES) - It sounds like the line-up for an eclectic all-star music festival: Jay Z, Katy Perry, Jon Bon Jovi, The National, Steve Aoki. And it is, almost, though the musicians will be spread across political swing states in the coming days, volunteering their services in support of Mrs Hillary Clinton.

The performance series, dubbed Love Trumps Hate, which will bring Jay Z (and "special guests") to Cleveland on Friday and Perry to Philadelphia on Saturday, is just one of the Clinton campaign's homestretch tactics for energising voters that relies upon pop stars.

Miley Cyrus canvassed with millennials at a Virginia university last week; rapper Pusha T appeared in a campaign video with Mrs Clinton's running mate Tim Kaine; and Cher recently hit the ground as a surrogate, as well.

Despite Mrs Clinton's predictable advantage in the generally left-leaning world of pop music - musicians publicly supporting Mr Donald Trump include Wayne Newton and Ted Nugent - the involvement of A-listers was not always a foregone conclusion in a presidential election between two widely unpopular candidates. Whereas Mr Barack Obama's national campaigns involved the enthusiastic support of entertainers from the start, neither Mr Trump nor Mrs Clinton seemed at first to foster the same zeal among musicians.

As with President Obama's upstart operation in 2008, many music-world figures put their initial approval behind the youth-driven Bernie Sanders and only later moved towards Mrs Clinton. Even now, major stars, including Taylor Swift, Kanye West and Beyonce, have not formally endorsed any candidate with only days to go, while other musicians have opted to align themselves only with non-partisan get-out-the-vote efforts.

"Politics can still be a dirty word," said Mr Andy Bernstein, the executive director for HeadCount, a non-profit group that works with musicians to register voters at concerts. "You have two candidates who are very polarising, and there's certainly many, many people in this country who don't have a positive view of either. That makes things interesting because musicians do not want to divide their fans."

Mr Scooter Braun, a manager for influential acts including West and Justin Bieber, has been outspoken about his support for Mrs Clinton. But he acknowledged that some of his clients had opted not to use their platforms for risk of "alienating part of their fan base who disagrees with them".

"It scares people," he said. "Now, if you put your convictions out there, you have all different sides and points of view hitting you up on social media."

But he called the idea that entertainers have a responsibility to enter the political fray - "It's time for Taylor Swift to say something about Donald Trump", read one recent headline - "absolutely ridiculous", adding: "I think these individuals should speak if they have the facts. But what is the point of using your loudspeaker if you're not passionate about what you're speaking about?"

Some, he added, "don't have a dog in the fight". "Justin's Canadian," he noted of Bieber. "I don't want to force anyone to take sides. If you don't know, then there's nothing to do but observe."

This turbulent election cycle prompted many musicians to take their time before wading in fully. Kid Rock and Blake Shelton each expressed early interest in Mr Trump, though they have avoided the campaign trail and most political social-media stumping. Mrs Clinton drew some pop-star support from the start, especially from singers like Perry, Demi Lovato and Barbra Streisand, but has leaned harder on musical surrogates lately.

"In the closing weeks, these artists have a powerful ability to energize, excite and mobilise our base," said Ms Adrienne Elrod, the director of strategic communications for the Clinton campaign.

On the other side, Newton, the Las Vegas entertainer, attended the final presidential debate last month in support of Mr Trump and has given interviews defending the candidate from accusations of sexual misconduct.

Mr Trump's most adamant musical supporter has been Nugent, the controversial rocker and National Rifle Association board member. In a campaign video released in September, Nugent warned that Mrs Clinton "will destroy the freedom that is uniquely American. Donald Trump will safeguard the things that make America the greatest place in the world". (Representatives for Mr Trump declined to comment.)

In 2008, Mr Obama galvanised outspoken entertainers early in the primary process: Yes We Can, the pro-Obama music video featuring Will.i.am, John Legend and Scarlett Johansson, was released that February.

"The way Obama engaged people was personal," Russell Simmons, the hip-hop mogul, recalled. "Valerie Jarrett started the process, put you on the phone with him. Early on, I got on a plane with Jay Z, Puffy, Beyonce, Mary J. Blige and other executives to lead the charge and cultivate enthusiasm."

As president, Mr Obama continued to build alliances with musicians, frequently discussing his listening habits and releasing personal playlists, while inviting of-the-moment artists like Frank Ocean and Chance the Rapper to the White House for events.

For Mr Trump and Mrs Clinton, such connections seemed, at least at first, to be less of a natural fit. "You had some really, really passionate advocates for Bernie Sanders" in music, said Mr Bernstein of HeadCount. The Vermont senator's website kept a dedicated page listing his artist supporters, including Michael Stipe, Lucinda Williams and Killer Mike.

But even after Mr Sanders' primary defeat and subsequent endorsement of Mrs Clinton, some artists turned their focus to the importance of voting or speaking against Mr Trump rather than for his opponent.

The 30 Days, 30 Songs project, which advertises itself as being by "artists for a Trump-free America" and features music by R.E.M. and Death Cab For Cutie, has included no outward mention of Mrs Clinton. California rapper YG, whose song FDT has been perhaps the most impactful political anthem this cycle, has also kept his focus on Mr Trump, while Bruce Springsteen, who performed at Obama rallies during the last two elections, has voiced his disapproval of the Republican candidate in interviews.

Ani DiFranco, the feminist folk singer, said that she is "way left of Hillary" and thus did not feel driven to endorse her. But she has been adamant about encouraging her fellow progressives to participate in some way. "Do not use Bernie as an excuse," she said.

Ed Droste of Grizzly Bear, another Sanders supporter, came around only after the second presidential debate last month. "I love @berniesanders and will always," he wrote on Instagram, "but you know what? I'm an adult and I see what's happening right now and it's frightening. #imwithher"

Other musicians found ways into the race via specific policy concerns.

"Artists don't like speaking on issues that they don't feel like experts on," said Mr Jesse Moore, the vice-president for civic engagement for Rock the Vote, which is known for its celebrity representatives. "At the same time, most voters and most people in politics aren't experts on everything. It's about putting artists in a position where they can speak about their own life experiences."

Rapper T.I. said a musician's influence was "best and most appropriately applied when it's sincere". Following the police killings of Philando Castile and Alton Sterling this summer, T.I. said he was motivated to begin speaking more about election issues affecting African-Americans, including prison and police reform.

"That touched something inside of me that urged me to get up and do something to inspire or promote change," he said. "Not just in my music, but with my actions."