Florida’s lawmakers are appealing to President Donald Trump in a renewed effort to get the Navy to home-port a nuclear-powered aircraft carrier at the Mayport Naval Station.

It’s a move that the Navy has long said it wants to make, but has said for the past eight years that it can’t afford.

So now, Florida’s senators, Republican Marco Rubio and Democrat Bill Nelson, are appealing further up the chain of command. The pair co-authored the Jan. 25 letter in an effort to get Trump to put money in next year’s defense budget, due out in February, to start the upgrades needed for a carrier to make the move.

“We urge you to include funding in the Fiscal Year 2019 Presidential Budget to support a nuclear-powered aircraft carrier at Naval Station Mayport,” the letter said. “The security, availability and redundancy of our aircraft carrier fleet is critical to our national security in light of increased global security threats.”

Mayport has home-ported multiple aircraft carriers over the years, and as many as two at a time through the 1990s. But the northeastern Florida base has been without a carrier since the Navy decommissioned the conventional aircraft carrier John F. Kennedy in 2007.

The letter notes that the Navy’s official position since a 2009 is to eventually home-port a carrier in Mayport. And Navy leaders have reiterated that stance over the years, but saying they just can’t afford the cost, yet.

The base can currently host nuclear carriers for visits of up to a month, but does not have the facilities to allow Navy’s largest ships as permanent residents. The price tag to upgrade Mayport to support a nuclear-powered carrier was projected in 2009 as costing between $500 million to $1 billion.

Some improvements were started in 2011, but since then no funding has been allocated to the effort to make the base a nuclear homeport, which could take as many as three to five years to accomplish.

Years ago, a carrier move was was initially announced by the Navy to happen in 2015 but was then put off, first to 2019, and then the move was postponed indefinitely because of budget cuts. Instead, the Navy moved three amphibious ships to the base in in 2013 and 2014. It also has made the base the East Coast home for littoral combat ships.

The justification for moving a carrier to Florida is what is called “strategic dispersal.”

It is how the Navy avoids keeping all of its eggs in one basket. Attack Norfolk, or somehow disable the ships or their ability to leave the base, and you’ve taken out the entire East Coast carrier fleet. Natural disasters also pose a threat.

Such is the case on the West coast where the Navy bases carriers in both San Diego and Bremerton, Washington.

“Strategic dispersal of our capital ships is a long held Navy requirement and only prudent considering the cost and strategic value to our national defense,” the lawmakers wrote. “The urgency of dispersing our East Coast fleet should not be underestimated.”