An Amtrak proposal to provide a one-seat ride from Ronkonkoma to Washington, D.C., with stops in Hicksville and Jamaica, is gaining momentum, having recently completed the first phase in a three-step study and winning support among elected officials and rail rider advocates.

But questions, and skepticism, remain over the need to extend the intercity rail network onto Long Island, when Long Island Rail Road travelers can already connect to Amtrak at Penn Station.

"I don’t see why you just can’t switch. Amtrak is right upstairs," said Steve Sisti, 66, of Bohemia, said.

While it remains unclear how much the project would cost Amtrak, project supporters say the needed investment would be minimal, but the potential upside of connecting Long Island to the Northeast rail corridor is huge.

Amtrak is largely funded by the federal government.

"It has a very distinctive benefit in that you're serving 3 to 4 million new people and you have just the cost of basically, relatively small improvements to one station," said Gary Prophet, president of the Empire State Passenger Association, an advocacy group for Amtrak riders in the region, referring to Ronkonkoma. "In a congested area like the Northeast, I think extending three trains a day — certainly there’s enough demand to do that."

Amtrak has been kicking around the idea for years. The proposal earlier this year concluded the first step in a Federal Railroad Administration program which funds the expansion of rail routes connecting U.S. cities.

In the next step, expected to begin later this year, Amtrak would explore "cost, feasibility and funding options," and coordinate with the LIRR on how it would implement the new service, Nicole Bucich, Amtrak’s vice president for network development, said. The final step would include preliminary engineering work and a federally regulated environmental study.

Although the first trains likely wouldn’t pull out until sometime in the 2030s, at the earliest, Bucich said Amtrak is "committed" to coming onto Long Island — a "natural extension" of its existing network.

"There is significant demand out there. Right now in order for folks from Long Island to travel to Philadelphia or Baltimore or D.C., they can take the train, but it does require a transfer," said Bucich, who emphasized the inconvenience of lugging baggage from the LIRR’s concourse in Penn Station to Amtrak’s above it, or to Moynihan Train Hall across the street.

"Not having to make that transfer makes a big difference in the ridership demand," Bucich said.

Under the plan, Amtrak would run three trains onto and off Long Island each day — for a total of six trips — as part of its Northeast Regional Service. They’ve noted that the infrastructure investment is relatively modest, as the tracks and stations are already there, owned and maintained by the LIRR. Bucich said Amtrak will look at whether it would "need additional tracks or platforms" at Ronkonkoma.

The new service also counts on Amtrak getting its new fleet of "Airo" trains that can operate on both overhead wires and diesel power, which would be required on the LIRR’s territory. The $7.3 billion new fleet isn’t expected to be in place for at least another five years.

Bucich said the added cost of traveling by Amtrak to or from Long Island, rather than Penn Station, has not been determined, but "it is going to be more expensive" than making the same leg of a trip on the LIRR. An off-peak LIRR ticket between Ronkonkoma and Penn Station costs $15.25.

Asked about Amtrak’s proposal, the Metropolitan Transportation Authority — the Long Island Rail Road’s parent organization — offered little, but drew attention to how many trains the LIRR already operates on that stretch of track.

"The Long Island Rail Road runs 50 trains to Ronkonkoma with even more going back to NYC every weekday," MTA spokesperson Aaron Donovan said in a statement. "We are working with Amtrak on its study."

Understanding capacity limitations during the rush hours at the LIRR — the busiest commuter railroad in North America — Bucich said Amtrak would "make sure that our trains are slotted to not impact their peak flows." Capacity on the LIRR’s Main Line, which stretches all the way to Greenport, has increased substantially in recent years as the MTA built a third track between Floral Park and Hicksville and a second track between Farmingdale and Ronkonkoma.

At the same time Amtrak looks to advance the proposal, it’s feuding with the MTA over operations at Penn Station, which is owned by Amtrak, but primarily used by the LIRR. Against the objections of the MTA, Amtrak last month took one of the four East River Tunnels to Penn Station out of service through late 2028 for repairs and upgrades.

The move could result in major service disruptions for Long Island commuters, LIRR officials have said.

Marc Herbst, the Suffolk County representative on the MTA Board, said he doesn't expect animosity between the two transportation agencies to stand in the way of Amtrak coming to Long Island. But he acknowledged the MTA is having some "responsible reluctance" over the plan.

"Of course, you have to look at scheduling in a careful manner, and I think that's what the MTA is concerned about. You can't infringe upon the daily commuters," Herbst said. "They want to make sure that, if this moves forward, it's done properly and doesn't impact our ridership."

Suffolk County Executive Edward P. Romaine urged the MTA to get on board with the plan, which he called "a great idea," as it would not only give his constituents new rail connections to other cities, but could also assist in making Suffolk County a destination for travelers.

"I think Amtrak coming to Ronkonkoma puts Ronkonkoma on the map," said Romaine, who noted that Amtrak’s proposal coincides with ongoing efforts to develop the area around Ronkonkoma Station and Long Island MacArthur Airport, including, by someday building a new convention center nearby.

Romaine said the addition of Amtrak would help transform Ronkonkoma into "a major transportation hub for Long Island," and the MTA should help in that effort by "upgrading their facilities."

At Ronkonkoma last week, LIRR travelers were split on whether linking Amtrak to the station was a worthwhile effort. Moments after stepping off a train that originated in Penn Station, Sisti expressed concern about the prospect of the LIRR having to share space with another railroad at Ronkonkoma.

"If it’s going to tie things up more here, that would be an issue," Sisti said.

Sameer Umar, 18, was excited about the prospect of a one-seat train ride from his home station to the nation’s Capital.

"I’ve thought about going to D.C. a couple of times, but obviously the idea of transferring at Penn Station, it’s pretty weird," Umar, of Bohemia, said. "I’ve always wanted to see more public transport around here. … Having Amtrak here would definitely be a step toward that."

At Amtrak's Moynihan Train Hall early last week, Carlos Flores, 38, said he believes the plan "makes absolutely no sense," even though he stands to benefit from it.

"I’m in a long-distance relationship. I go to D.C. every other weekend. And I live close to Jamaica. It would be great for me, instead of having to come here," said Flores, of Woodhaven. But he believes cases like his are few and far between. "You’re not going to tell me that there’s enough business or demand from Ronkonkoma to Jamaica to justify the amount of money to be spent," he said.

Prophet, of the Empire State Passengers Association, said he believes with time all sides will come to appreciate the significant benefits of bringing Amtrak to Long Island, including the LIRR, which stands to gain new customers from rail travelers throughout the Northeast connecting to their trains.

"Now, depending on where you’re going on Long Island, it requires three trains to get out there if you’re coming from New Jersey, for example," said Prophet, who believes Amtrak could be a gamechanger for potential Long Island visitors scared off by its jam-packed roadways. "It’s not an easy place to drive, and the people who don’t need to, just don’t go out there."