Hamas on Thursday chose Ismail Haniyeh, a Hamas leader widely viewed by Palestinians as a pragmatist, to be the next Prime Minister, a senior official in the militant group said.Haniyeh headed Hamas’s list of candidates in the January 25 parliamentary election in which the movement, dedicated to Israel’s destruction and pledged to fight corruption, scored a landslide victory. ‘‘We have decided to nominate brother Ismail Haniyeh as the prime minister,’’ said the senior official after Hamas’s elected legislators met in the West Bank city of Ramallah. The official spoke on condition of anonymity because Hamas has yet to make a formal announcement. He said the nomination was made after consultations with Hamas officials in the Gaza Strip.