JAKARTA, March 2 (Reuters) - One of Indonesia's leading presidential candidates on Thursday pledged to continue President Joko Widodo's flagship $32 billion new capital city if he wins a 2024 election, giving a boost for an ambitious project hit by delays and investor uncertainty.

Anies Baswedan, a popular former Jakarta governor who is backed by three political parties, said a law had been passed by parliament to build Nusantara, as the new capital is known, so whoever wins the presidency must see it through.

"The new capital city is not only an idea. This has become a law and all of us, when being inaugurated for any position, our vow is to implement the law," Anies said at a public event when asked about his commitment to the new capital on Borneo island.

Jokowi, as the president is popularly known, announced the project in 2019, arguing that Jakarta was congested and sinking.

But Nusantara has faced some problems, including delays due to the pandemic and doubt among some investors that Jokowi's successor would stick with it.

The Indonesian Centre for Strategic and International Studies last year found nearly 59% of 170 experts it interviewed were unsure Nusantara would materialise, citing uncertainty about funding and management.

Jokowi hopes to rely mainly on private funding for the capital, with 20% from state coffers.

Anies has been ranked in the top three for all major polls on preferred presidential candidates in the past year.

Registration for candidates has yet to open.

Central Java Governor Ganjar Pranowo was the frontrunner according to a survey by pollster Litbang Kompas conducted in January, backed by 25.3% of the 1,202 respondents.

Second was Jokowi's defense minister, Prabowo Subianto, with 18.1% and Anies third on 13.1%.
(Reporting by Ananda Teresia and Stefanno Sulaiman Editing by Gayatri Suroyo, Martin Petty)