Updated: 6:01 p.m.

The Architect of the Capitol has a $1.5 billion backlog of maintenance projects and a tight operating budget, but it has made the first phase of restoring the aging Capitol Dome a priority.

The AOC announced Thursday that it has begun renovations on the skirt of the iconic structure. The lower level of the cast-iron Dome has sustained almost 150 years of weather damage, and restoration is needed to prevent it from further deterioration that could lead to safety hazards.

“There is only one Capitol Dome, and we are committed to preserving it for generations to come,” Architect of the Capitol Stephen Ayers said in a statement.

Earlier this year, prospects for renovating the Dome seemed dim.

The Senate Appropriations Subcommittee on the Legislative Branch slated $20 million for Dome repairs in its fiscal 2011 allocation, subcommittee Chairman Ben Nelson (D-Neb.) said. However, with all spending bills bogged down in both chambers, the necessity of passing a short-term funding measure loomed to keep the federal government afloat, and it appeared that the repair money would not be made available.

But Nelson, in a departure from his role as a fiscal hawk who wants the legislative branch to lead by example, hinted in March that renovating the Capitol Dome would be prioritized even as the AOC’s overall budget would be reduced from the previous fiscal year.

“If we do put it off, obviously, deferred maintenance has its challenges,” Nelson said. “We are going to have to do it.”

Funding for Phase I of the Dome renovation was ultimately included in the House- and Senate-negotiated stopgap spending measure passed in April.

But then there was the question of timing, as lawmakers and the AOC tried to reconcile the pressing need to renovate the Dome with budgetary constraints and a hovering deadline. The renovations would have to be completed by the 2013 inauguration to avoid the eyesore of scaffolding around the Dome that provides the majestic backdrop for the presidential swearing-in ceremonies.

With the project officially under way after several months of preparation “behind the scenes,” however, the restoration of the Dome skirt is scheduled for completion by next fall, with the second phase of renovation on the rest of the Dome to come following the 2013 inauguration, AOC spokeswoman Eva Malecki said.

Visitors to the Capitol should expect a partly obstructed view of the Dome in the meantime, however, as restoration of the structure’s ironwork, sandstone and brick masonry continues.

A scaffold tower is in place on the West Front grounds, and a second scaffold will soon be erected at the terrace level, according to the AOC’s news release. Much of the work will be done at night and on weekends to keep disruption to a minimum.