WASHINGTON (AP) — Under President Dwight D. Eisenhower, the nation prepared for the 50th birthday of the National Park Service with a spending splurge that refurbished Independence Hall in Philadelphia and helped complete the Gateway Arch in St. Louis and the 469-mile Blue Ridge Parkway. Next year, the world-famous system turns 100 and the celebration will be far more modest.

The Obama administration and Republican lawmakers have vastly different ideas about what to do.

Both parties agree that the country’s national parks and historic sites could use some sprucing up. Their shared goal is to use the centennial to improve trails, visitor centers, campgrounds and other park features that need maintenance work.

The question is how much of a dent Congress will make in a system-wide maintenance backlog with an estimated $11.5 billion price tag.

President Barack Obama has recommended spending an additional $1.5 billion on the parks over a three-year period. Republican leaders in Congress have a smaller birthday present in mind.

Just the fact they are open to greater investment, though, is being viewed as a promising first step by some Democrats.

Areas of agreement include lifting the price of the $10 lifetime park pass for seniors to $80 and enacting a lodging tax for those who stay overnight, though how much and whether it should apply to campers as well as hotel guests, will have to be worked out in the months ahead.

The administration and lawmakers are also looking to use some of the additional federal dollars to leverage private-sector donations and endowments.

Lawmakers go into the debate with different views on why the parks system is failing to keep up with basic maintenance. Republicans point to Congress’s appetite for adding new units to the parks system, diluting the pot of federal dollars into ever-smaller slices.

“It’s fun and sexy to add a new unit to the Park Service. It’s not fun or sexy to talk about fixing a sewer system,” said Rep. Rob Bishop, the Republican chairman of the House Natural Resources Committee.

Democrats say Congress has simply failed to make the national parks a priority. The budget over the past five years has been largely flat, increasing from $3.16 billion to $3.24 billion, though Congress did just boost spending by more than $200 million in this year’s budget.

Complaints about the backlog extend decades. For instance, President George W. Bush noted during a 2001 speech at Everglades National Park that “many parks lack the resources they need for basic care and maintenance.” He promised to restore and renew America’s national parks. At the time, the maintenance backlog stood at about $5.5 billion. The September 11 terror attacks would soon upend the nation’s spending priorities though.

Most of the nation’s 409 park units have a piece of the backlog.

Alcatraz, the former federal prison in California, has crumbling walls and deteriorated windows. “The walls leak, concrete falls off the building, rust jacking is causing the building to move and crack…,” the National Park Service said in a report to Congress this past year detailing its budget requests.

Mammoth Cave in Kentucky needs to have dirt trails replaced for safety reasons. “Without this project, the park may have to severely curtail visitor access to Mammoth Cave and eliminate significant visitor experiences,” the Park Service said.

And a historic hotel at Glacier National Park needs a new fire sprinkler system and other work. “Failure to rehabilitate this building will pose serious health and life safety threats to park visitors and park and concession employees,” the Park Service wrote.

Congress is just beginning to take a closer look at the administration’s request for more money and the debate will extend well into 2016. In a recent hearing, Republican Sen. Lisa Murkowski, chairman of the Senate Energy and Natural Resources Committee, called the backlog a travesty, but said spending $1.5 billion without identifying how most of that money would be raised was troubling. Other Republicans agreed.

Meanwhile, draft legislation that Bishop is putting together provides too little help, Democratic lawmakers said when reviewing it.

“Making a dent in the maintenance backlog is going to require a significant investment,” said Democratic Rep. Niki Tsongas of Massachusetts. “New revenue generated by fees will not solve this problem.”

Lawmakers from both parties are interested in using federal dollars to generate more private sector investments in the parks. They want to follow the model of a program called the Centennial Challenge in which the federal government spent $10 million and other groups and individuals pitched in about $16 million.

Obama has upped the ante, calling for federal spending of up to $100 million over each of the next three years to be matched with private contributions from individuals, foundations or businesses.

“It’s essential the federal government have skin in the game. The first question I get from prospective donors: Is the Park Service invested?” said Will Shafroth, president and CEO of the National Park Foundation, a charity that raises money for park improvements.

The big-ticket item in Obama’s request is $900 million that would address non-transportation infrastructure. Roads and bridges make up about half of the maintenance backlog, and administration officials will use the recently passed highway bill to direct more money there.