Who will Donald Trump pick as his vice-president?

Donald Trump is the unofficial Republican presidential nominee (the party still must formally approve him at its convention this summer) and the competition to join his ticket has been heating up.

Allies and even some former rivals of the ex-president have pledged their loyalty and rallied his supporters on the campaign trail, with some openly auditioning for the role.

Mr Trump, for his part, has teased crowds with a range of options, but if tradition holds we still have months before learning his selection. The only thing that seems certain is that Mike Pence, his former vice-president, will not be joining the ticket. Mr Pence ran against Mr Trump in the primaries, largely motivated by the 6 January 2021 Capitol riot, and has sharply criticised his former boss.

Here's a look at the Republicans rumoured to be in the so-called veepstakes:

Near the top of the pack of hopefuls is New York congresswoman Elise Stefanik.

Once a moderate, Trump-hesitant Republican, Ms Stefanik, 39, has drifted closer to the right wing of her party in recent years, becoming one of Mr Trump's most loyal defenders.

Now the highest-ranking woman among House Republicans, Ms Stefanik has also risen to modest conservative fame - first for her work on Mr Trump's first impeachment defence team in 2020 and, more recently, for her viral take-down of two Ivy League college presidents.

"Elise became very famous," Mr Trump told supporters recently of her contentious questioning of the college leaders. "Wasn't it beautiful?"

Ms Stefanik certainly seems open to it, telling reporters she would be "honoured" to serve in the Trump administration "in any capacity".

Tim Scott, an erstwhile competitor for the Republican nomination, is a senator and one of the most prominent black Republicans in the US.

He pitched himself as an optimistic conservative but his campaign failed to gain traction with voters. In November, after three lacklustre debate performances, he exited the race.

Mr Scott, 58, seemed to throw his hat into the vice-presidential ring in January with his endorsement of Mr Trump - giving the cold shoulder to his fellow South Carolinian Nikki Haley, the woman who appointed him to the Senate in the first place.

But it was Mr Scott's rousing remarks at a Trump campaign rally ahead of the New Hampshire primary that pushed his name firmly into the VP conversation. "We need Donald Trump," Mr Scott told voters.

He then appeared on stage with Mr Trump during his victory speech, standing directly behind him in the television shot. At one point, he said to Mr Trump: "I just love you." The former president responded: "That's why you're a great politician."

In more recent appearances together, Mr Trump has lauded the South Carolina lawmaker as "much better [at advocating] for me than he was for himself".

JD Vance, 39, the junior senator from Ohio, was also in New Hampshire rallying support on behalf of Mr Trump.

The Yale-educated ex-venture capitalist first made headlines for his best-selling book Hillbilly Elegy, a memoir that followed his working class upbringing in the rust-belt Midwest.

Mr Vance, once a self-identified "never-Trumper", refashioned himself when he launched his 2022 Senate bid as a loyal disciple of Mr Trump. It paid off: Mr Trump's endorsement of Mr Vance gave his campaign a critical boost in both the crowded Republican primary and the general election.

Now in office, he has championed the issues that animate Mr Trump's base.

Mr Vance has said that he would be of better use to Mr Trump in the Senate, but he doesn't seem to have ruled out being vice-president. "I want to help him however I can," he said.

A South Dakotan who dropped out of college to run the family farm, Kristi Noem served as her state's lone member in the House of Representatives for eight years and was elected its first female governor in 2018.

The position has helped Ms Noem elevate her national profile in conservative circles, especially when she flouted mask mandates and other restrictions during the pandemic era.

Salacious reports of a long-time extramarital affair with former Trump campaign manager Corey Lewandowski have threatened to derail the 52-year-old's ambitions.

But Ms Noem has held a cosy relationship with Mr Trump - who she says is "confident in who he is" - and he confirmed to Fox News that her name is on his shortlist.

One of the biggest surprises on the rumoured list is the Florida senator Mr Trump derisively dubbed "Little Marco" during the 2016 presidential campaign. In the primaries that year, Senator Rubio had joked about Mr Trump having small hands, which stoked Mr Trump's ire.

But since that election the two men worked together and Mr Rubio endorsed Mr Trump early on in this primary season. The son of Cuban immigrants, he could help win over the Latino vote, and with his history in the party (he was also floated as a potential running mate to the 2012 Republican nominee Mitt Romney) he could solidify the support of mainstream Republicans.

There is an obstacle to him being picked: his home address. Under the US Constitution, a vice-presidential candidate cannot reside in the same state as the presidential candidate. Both men live in Florida.

The first-term senator from Alabama appeared to audition for vice-president in giving the Republican response to President Joe Biden's state of the union this year. While the speech delivered from her kitchen drew criticism even from conservatives, Mr Trump was reported to have been happy with her address, where she spoke about immigration and economics.

Since her arrival in Washington DC, Ms Britt has taken a position on the powerful Senate appropriations committee and worked as a key fundraiser for more senior colleagues. Among Democrats, she has won some approval by working on a bipartisan bill prohibiting children under 13 from using social media and visiting John Fetterman when the Pennsylvania senator checked into hospital to seek treatment for depression.

She is not a natural ally for Mr Trump, though. She was the last member of Alabama's congressional delegation to endorse the 77-year-old in December, and observers note that her political views have been more temperate than his.

Byron Donalds, 45, is another fresh face on the national scene - and one who has helped raise the profile of black conservatism.

Born in New York to a single mother, Mr Donalds worked in banking, insurance and finance before entering local politics in Florida in 2012.

After four years in the Florida House of Representatives, he has served since 2020 in the US House, representing the right-wing flank of his party in Washington.

Asked in November if he would accept the role of vice-president in a second Trump term, the congressman said: "I mean, who wouldn't?"

The first ever Hindu member of the US Congress, former Hawaii congresswoman Tulsi Gabbard may be the biggest dark horse on Mr Trump's shortlist.

A decade ago, the Iraq War veteran and US Army reservist served as vice-chairwoman of the Democratic National Committee - before resigning to endorse Bernie Sanders's 2016 presidential campaign.

Her time in Congress, from 2013 to 2021, was marked by frequent criticisms of the Obama administration and US military interventionism, including a controversial decision to meet with Syrian leader Bashar al-Assad.

She ran in the 2020 Democratic presidential primary, with her most notable moment being a fierce critique of Kamala Harris - now the vice-president - over her past as a prosecutor in California.

Ms Gabbard, 42, was the last to drop out of that race, endorsing Joe Biden. But she has since taken on several conservative positions, beefed up her contributions to Fox News and announced in 2022 that she was leaving the Democratic Party.

The Washington Post reported earlier this month that Mr Trump has spoken with Ms Gabbard - an outspoken critic of Ukraine aid - about foreign policy and managing the Pentagon.