4 months after Maria, 450K residents of Puerto Rico still without power

— -- It's been more than four months since Hurricane Maria devastated Puerto Rico, and nearly half a million customers are still without power, the Army Corps of Engineers said today.

Some 4,000 power restoration personnel are currently working to repair the electricity to more than 450,000 customers. An additional 1,000 workers -- along with hundreds of bucket trucks and transformers -- are expected to arrive on the island to "accelerate progress" in the next few week, according to the Corps.

"We will continue to press forward until the mission is complete," Task Force Power restoration commander Col. John Lloyd said in a statement.

In concert with the Puerto Rico Electric Power Authority (PREPA), the Federal Emergency Management Agency (FEMA), and industry workers from the mainland, the Corps has already restored power for 1 million customers.

Puerto Rico Gov. Ricardo Rossello recently announced plans to privatize the power authority, which was struggling even before Maria knocked out the island's entire power grid.

The post-hurricane power restoration effort hit a snag shortly after PREPA awarded a $300 million restoration contract to Whitefish, a Montana-based company with just two full-time employees, rather than the mutual-aid network of public utilities usually called upon to coordinate power restoration after disasters.

After FEMA expressed "significant concerns" over the procurement process and questioned the hourly rates outlined in the contract, PREPA canceled the contract. Whitefish halted work shortly thereafter.

ABC News' Josh Hoyos contributed to this report.