Its been nearly five months but there is no definitive word yet on who President Trump's new secretary of the Navy will be, and experts say that's soon going to start having an impact on one of Trump's signature campaign promises: a bigger, more deadly Navy.

Trump's first nominee, financier Philip Bilden, dropped out of consideration in late February after he proved unable to fully disentangle his complex financial ties from a career spent in Hong Kong. Now Trump's new presumptive nominee, a former Marine pilot and financier Richard Spencer, is also caught up in a mess of financial entanglements that have proved tricky to unwind, according to two sources with close knowledge of the situation.

While there is no immediate indication that Spencer intends to withdraw his name from consideration, there can be no doubt that Trump has had difficulty filling the top civilian jobs in the Army and Department of the Navy. Trump's first nominees for Army and Navy secretary both dropped out citing business and financial ties, and last week Trump's second Army secretary nominee, Mark Green, withdrew in a wave of controversy over statements about transgender service members and Muslims.  

New Air Force Secretary Heather Wilson was confirmed by the Senate Monday, the first nominee at the Department of Defense to be confirmed since James Mattis. Congress and defense experts say that if Trump is serious about growing the fleet, he's going to have to move on filling the rest of the top spots in the department, which will include the undersecretary and a slate of assistant secretaries.

Sean Stackley, the current acting secretary, is widely respected in and around the Pentagon, but his non-permanent status will make him hesitant to make any big decisions that could hem in a permanent Trump selection, said Bryan Clark, a retired submarine officer and analyst with the Center for Strategic and Budgetary Assessments. As the Navy looks to grow it's going to need to make trade-offs about what the service is not going to buy anymore, and once a program is canceled or significantly altered, those decisions can be tough, if not impossible to reverse.

"A holdover is just not going to be comfortable making big decisions on behalf of the new administration," Clark said.

That's going to quickly be important, since the Navy is getting ready to roll out its 2018 budget and is already well into compiling its 2019 budget, Clark said.

Bryan McGrath, a retired destroyer skipper and defense consultant with The Ferrybridge Group, went a step further, saying that the continued delays could imperil Trump's promised naval buildup. A permanent political appointee would have buy-in from the administration and some clout with Congress and the Office of the Secretary of Defense that an acting secretary just doesn't have.

"It means there is not an empowered individual with agency who can argue for the service's priorities within OSD and on Capitol Hill," McGrath said. "It means the necessary increase in the size and capability of the Navy is jeopardized, which is something Trump laid out as both a national security and a political goal."

Selling the buildup is going to be an important job for the SECNAV, something Mattis can't get done on his own with a whole DoD to run, said Michael O'Hanlon, a defense analyst with the Brookings Institution, a Washington think tank. That was one of former Navy Secretary Ray Mabus's key achievements in the job, he said.

"Secretary Mabus helped ramp up the shipbuilding plan of Obama ... and could keep clearer focus on it than could the SECDEF or the White House itself," O'Hanlon said. "So to the extent the Trump administration wants a similar initiative, it needs someone to give it logic and cogency and a sustained [public relations] and political boost. That’s [an] important reason for a strong secretary of the Navy."

The new administration is lagging behind the pace set by the Obama administration, which nominated its Navy secretary, Mabus, in late March and had him sworn in on May 19, 2009. Congress is starting to take notice and there is a growing chorus within Trump's own party calling for action.

Sen. Lindsey Graham, R-S.C., and an influential member of the Senate Armed Services Committee, said Tuesday that he wanted to see the process move.

"If I were them I'd speed it up because the world is a very dangerous place," Graham said. "We need all hands on deck."

Sen. Tom Cotton, R-Ark., and also a SASC member, told conservative radio host Hugh Hewitt, "That makes it hard for Secretary Mattis ... to drive the president's priorities in [his] department ... I would urge everyone involved in the administration ... to start getting us those nominations in a faster form."

Defense News writer Joe Gould contributed to the reporting of this story.