There are fears Prince Harry's upcoming wedding could damage US-UK ties - and US President Donald Trump could be the reason.
The prince and fiancée Meghan Markle have told aides they want former President Barack Obama and his wife to attend.
But officials fear Mr Obama's invite to the royal wedding could be seen as a snub to Mr Trump, the Daily Mail reports.
As the wedding is not a state occasion, the guest list will be drawn up by Buckingham Palace, rather than the government.
Mr Trump is reportedly unlikely to get his own invitation.
"Harry has made it clear he wants the Obamas at the wedding, so it's causing a lot of nervousness," a senior government source told The Sun.
"Trump could react very badly, if the Obamas get to a royal wedding, before he has had a chance to meet the Queen."
Relations between the UK and the US are already at a low, after Prime Minister Theresa May rebuked Mr Trump for retweeting British far-right anti-Islam videos.