DAMASCUS, Syria (AP) — A massive double car bombing and a mortar strike targeted pro-government neighborhoods Tuesday in two of Syria’s largest cities, killing at least 54 people a day after President Bashar Assad declared his candidacy for re-election.

The attacks in Damascus and Homs heightened fears of an escalation ahead of the contentious June 3 vote and showed that despite a series of battlefield setbacks, the rebels remain capable of hitting the government and its core of support.