President Donald Trump is set to make his first visit to Puerto Rico, two weeks after Hurricane Maria devastated the US territory, and is likely to face more criticism of his handling of the disaster as the vast majority of the island's inhabitants lack power and phone service and are scrambling for food, clean water and fuel.
San Juan Mayor Carmen Yulin Cruz led the attack on the administration's response on Friday, criticising an official's description of relief efforts as a "good news story" and urging Trump to act more decisively.
Trump fired back at Cruz on Twitter, accusing her of "poor leadership".
It's not clear if the two will meet when Trump arrives on Tuesday.
"(Cruz) has been invited to participate in the events tomorrow and we hope those conversations will happen and that we can all work together to move forward," White House spokeswoman Sarah Huckabee Sanders said on Monday.
Trump is due in Las Vegas on Wednesday to meet people affected by Sunday's mass shooting.
Puerto Rico's governor said there had been progress in getting fuel supplies to the island's inhabitants as they faced a 13th day largely without power.
About five per cent of customers in Puerto Rico had their power restored by mid-morning on Monday, including San Juan's airport and several hospitals.
Mobile phone service is still elusive, with more almost 90 per cent of mobile phone sites down.
FEMA Administrator Brock Long said things were improving with traffic moving and businesses reopening.
"I didn't see anybody in a life-threatening situation at all," he said.
"We have a long way to go in recovery" and he said rebuilding Puerto Rico was "going to be a Herculean effort".
