While few would argue that Portland’s school facilities are in need of repair, a debate is ongoing about how best to pay for the upgrades and whether a multimillion-dollar bond to rebuild four elementary schools will address the district’s most urgent needs. Support is building to ask Portland taxpayers to borrow $61 million to rebuild Presumpscot, Reiche, Lyseth and Longfellow elementary schools, which have not seen major investments since they were built about 45 to 65 years ago.