RAMALLAH — The Palestinian president said Tuesday he is optimistic that US Secretary of State John Kerry will succeed in restarting Israeli-Palestinian peace talks, a rare upbeat assessment about ongoing American mediation efforts. Mahmoud Abbas' comments came two days after Kerry ended his latest peace mission to the region without any breakthroughs. While Kerry said he had narrowed the gaps between the sides, the lack of any visible progress has led to widespread pessimism on both sides. Abbas said Kerry presented "useful and constructive suggestions" and promised to return to the region within the next week or so. In the meantime, Kerry has left senior aides in the region to continue his mediation efforts. "We are optimistic because he is serious and determined to reach a solution," Abbas said. The Palestinian leader addressed reporters at a news conference with visiting Italian Foreign Minister Enrico Letta. Since taking office early this year, Kerry has been shuttling between Israel and the Palestinians in search of a formula for restarting peace talks, which have been stalled for nearly five years. Before departing, Kerry said he had made significant progress in bringing the sides back to the negotiating table. But he declined to provide any details on the "package" he is working on, and asked both sides to keep quiet out of respect for the negotiating process. The last substantive round of talks broke down in late 2008, shortly before Israeli Prime Minister Benjamin Netanyahu took office. The Palestinians have demanded that Netanyahu stop building in Jewish settlements in the occupied West Bank and East Jerusalem before talks resume. The Palestinians claim both areas, seized by Israel in 1967, as parts of a future state. — AP