Republican Donald Trump has reportedly chosen Indiana Governor Mike Pence as his vice presidential running mate, in a move that will put at Mr Trump's side a conservative with the potential to unify divided Republicans.
The presumptive Republican presidential nominee is to announce his choice in Manhattan today.
The choice of Mr Pence was first reported by Roll Call and the New York Times and CBS also said this was his pick.
Mr Trump is to be formally nominated as the party's candidate for election at the Republican National Convention next week in Cleveland.
Traditionally, the vice presidential choice is used to build enthusiasm among party loyalists.
Mr Trump's choice of running mate is seen as critical because his defeat of 16 rivals in the Republican primary race left the party divided and some party leaders are still uneasy about some of his campaign positions and his style.
Roll Call said Mr Trump was reportedly impressed with Pence's calm demeanour, his experience on Capitol Hill and as a governor, and Pence's potential to assist in governing if Mr Trump, who has never held elected office, wins in November.
Mr Trump had also considered former House of Representatives Speaker Newt Gingrich and New Jersey Governor Chris Christie as finalists.
Mr Pence, 57, a former congressman, is seen as a safe choice, not too flashy but popular among conservatives, with Midwestern appeal and the ability to rally more party faithful behind Mr Trump.
Mr Pence and Mr Trump spent time this month testing their chemistry at Trump's golf course in New Jersey and at the governor's residence in Indiana, Roll Call said.
Mr Pence had backed a Trump rival, Senator Ted Cruz of Texas, in April before the Indiana primary, but he praised Mr Trump and said he would work on behalf of the eventual Republican nominee.
Mr Trump won Indiana anyway, prompting Mr Cruz to drop out of the party race to be the nominee for the election.
Mr Pence had considered running for president himself in 2016 before deciding to run for re-election as governor.
Conservatives had urged him to seek the White House, but missteps in 2015 related to an Indiana law seen as anti-gay hurt his national profile.
This year, he was the target of a mocking social media campaign by women outraged at a law he signed creating new restrictions on abortions.
In an unusually public process of making his choice of running mate, Trump, 70, sat down with both Mr Pence and Mr Gingrich separately in Indianapolis on Wednesday.
Trump adviser Ed Brookover told CNN that Mr Trump "first and foremost" wants a running mate who he has good chemistry with and someone who can help him govern best.