Meb Keflezighi tweeted a photo of himself on the phone with the president.
Reps. Joe Kennedy, Stephen Lynch and Kyrsten Sinema are taking part in Monday's race.
The vice president spoke on the one-year anniversary of the marathon attack.
Obama said today's runners showed the meaning of "Boston Strong."
Reps. Joe Kennedy (D-Mass.) and Kirsten Sinema (D-Ariz.) will take on the 26.2-mile course Monday.