Democrats have final say on whether any of the eight witnesses on the GOP list will be called to testify in public.

Rep. Adam Schiff, who is leading the impeachment investigation on behalf of Democrats, said in a letter Wednesday that Republicans had to provide a witness list within 72 hours, along with a detailed explanation for why they are relevant to the impeachment inquiry.

Rep. Devin Nunes, the ranking member of the House Intelligence Committee, told Schiff that any "failure to fulfill Minority witness requests shall constitute evidence of your denial of fundamental fairness and due process" in his letter Saturday.

Democrats have already scheduled three diplomats to begin public hearings next week.

Here is the Republican list:Hunter Biden: The son of former Vice President Joe Biden, and a former board member for Burisma Holdings, a Ukrainian gas company that has been plagued for years by corruption concerns. President Donald Trump asked Ukraine's president in a July 25 phone call to consider investigating whether Joe Biden pressured the Ukrainian government in 2016 to shut down an investigation of Burisma.