The head of the Arab League arrived here Friday for talks with Syrian officials, who wield a great deal of influence in Lebanon, on an Arab plan to solve the deepening Lebanese political crisis. Amr Moussa crossed into Syria by land after three days of talks with Lebanese politicians to end their 15-month political crisis, the worst since the end of that country's 1975-90 civil war. "We are making progress in solving the crisis," he told reporters on his arrival. "There is still a possibility of reaching a solution if there is good will." Syria is a key player in Lebanon and backs the opposition, led by the militant Hezbollah group, against Prime Minister Fuad Saniora Western-supported government. Moussa is expected to meet with President Bashar Assad, Vice President Farouk al-Sharaa and Foreign Minister Walid al-Moallem.