EDMONTON- The federal New Democrats are holding a three-day caucus retreat in Alberta’s capital, a place where the party would like to grow its support. The NDP caucus is set to talk about health care, affordability and the party’s next national campaign as MPs get ready for Parliament to return next week. On Monday, NDP Leader Jagmeet Singh went door-knocking with Edmonton Centre candidate Trisha Estabrooks, a riding the party is hoping to win in the next election. Jennifer Howard, Singh’s chief of staff, says the party will also discuss their confidence-and-supply agreement with the minority Liberal government. That deal will see the NDP support the Liberals on confidence and budgetary matters until 2025 in return for movement on key priorities. The NDP touts the federal dental-care program and a…