The political leaders said: "As you near the finishing line, congratulations to you both on a magnificent race.
Thousands of people have gathered in the French port of Les Sables d'Olonne to greet Michel Desjoyeaux, who is on course to complete the Vendee Globe round-the-world-yacht race in a record time.
The race covers more than 40,000km (25,000 miles) through tropical and Arctic climates and is regarded as a serious test of endurance.
Competitors battle solo against the elements for more than three months, sleeping in 15 to 20 minute bursts.
Congratulations
Both Desjoyeaux and MacArthur have received e-mails from the three leaders at the Franco-British Summit: UK Prime Minister Tony Blair, French President Jacques Chirac and French Prime Minister Lionel Jospin.
The political leaders said: "As you near the finishing line, congratulations to you both on a magnificent race.
"Your courage, determination and skill have been in the best tradition of our two great maritime nations."
MacArthur, who is currently second in the round-the-world race, is limping to the finishing line after rigging which was strengthening her mast snapped on Wednesday evening.
She is likely to be second in the gruelling race and is set to break the record for a woman circumnavigating the globe.
Assuming her mast holds out, she is expected to cross the finish line on Sunday evening.
Webcam
People have been able to follow her efforts on the internet, via a camera on her yacht.
Desjoyeaux has estimated his arrival time as 1900 GMT.
He had hoped to cruise in ahead of a weather front but it has passed him by, leaving him wallowing in lighter, variable winds.
If Desjoyeaux fails to arrive by 2100 (2000 GMT), he will have to wait until the next tide in the early hours of Sunday morning before he can dock at the arrival pontoon.
Leading positions in the Vendee Globe solo round-the-world yacht race on 10 February:
1. PRB, Michel Desjoyeaux, 91 miles from the finish
2. Kingfisher, Ellen MacArthur, 190 miles behind the leader
3. Sill Matines La Potagere, Roland Jourdain, 887 miles
4. Active Wear, Marc Thiercelin, 1,216 miles
5. Union Bancaire Privee, Dominique Wavre, 1,684 miles
6. Sodebo Savourons la Vie, Thomas Coville, 1,706 miles
7. Whirlpool, Catherine Chabaud, 2,100 miles
8. Team Group 4, Mike Golding, 3,119 miles
9. EBP - Esprit PME - Gartmore, Josh Hall, 3,176 miles
10. Voila.fr, Bernard Gallay, 3,242 miles