U.S. Senator John McCain has said, 'Thanks, but no thanks,' to a job offer from Ukrainian President Petro Poroshenko.
The Ukrainian leader had asked McCain, among other leading officials, to join an advisory council to help Ukraine craft reforms and secure global support.
But in a statement on his website, McCain said constitutional constraits prohibited from accepting the offer.
In declining the offer, McCain said he will "continue to do everything" he can to stop what he called Russian President Vladimir Putin's "unabated agression" against Ukraine.
McCain has been one of the most vocal backers for sending U.S. arms to Ukraine.
The Advisory International Council of Reforms is to be headed by Mikheil Saakashvili, the former president of Georgia, and will also include Elmar Brok, a member of the European Parliament, and economist Anders Aslund.