Donald Trump is expected to name a conservative Catholic as his vice-presidential running mate following intense media speculation.

Indiana governor Mike Pence is regarded as a safe pick for Trump, whose unpredictability and frequently outlandish statements have alarmed the Republican establishment and led to many senior figures disowning him.

Pence served for 12 years in the US House of Representatives and has solid legislative experience and Trump's team will hope he will bring votes from the crucial Mid-West battleground states.

Pence is one of three candidates thought to be on Trump's shortlist, with former House speaker Newt Gingrich and New Jersey governor Chris Christie. He had not been confirmed as Trump's pick at the time of writing, but sources close to the Trump campaign said he had accepted an offer to run.

Pence backed Ted Cruz during the primaries. He is a committed believer, describing himself as a "pretty ordinary Christian" and as "a Christian, a conservative and a Republican, in that order." Pence grew up in a Catholic family and served as an altar boy, but also attended an evangelical megachurch before returning to Catholicism.

He backed conservative causes during his time as a congressman, opposing an extension of abortion rights and federal spending on stem cell research and cutting off funding for the controversial Planned Parenthood organisation.

Pence clashed with Catholic authorities when as governor of Indiana he halted state support for relocating refugees. The archdiocese of Indiana welcomed a Syrian family to the city anyway.

He was also caught up in the contentious religious freedom issues that have affected several US states because of his support for his state's Religious Freedom Restoration Act, billed as protecting religious rights against those of LGBT people. After major businesses and organisations threatened to boycott the state he was forced to sign a revised version.