The Race2Recovery team is trying to complete the Dakar Rally to raise funds for Help for Heros.
The charity is raising funds for the Tedworth House recovery and rehabilitation centre in Wiltshire.
The two US Marines involved with the race are also raising funds for the Heros Project which supports injured service men and women in America.
More top news
Stephen Barclay says Mr Tusk is clearly opposed to Brexit.
It is the start of the couple’s third tour to the country.
He said this means voters can be certain his party will deliver Brexit.