If US President Donald Trump seemed especially cheerful during Thursday night's events aboard the Intrepid marking the Battle of the Coral Sea, there's a reason.

The President is basking in the glow of the biggest legislative win of his young presidency.

The Republican-controlled House of Representatives narrowly approved a bill which would repeal and replace the Affordable Care Act.

The bill now goes to the Senate where its fate is by no means certain. But a win is a win, and this one was especially sweet for Mr Trump.

The first attempt to get rid of Obamacare back in March never got to a vote, pulled by Republicans amidst fears 24 million Americans would lose their health coverage.

Amendments won over enough Republicans for the new version to squeak through 217 to 213.

Democrats have their eyes on a different number: 1,278 and counting.

That's the number of days until November 3, 2020, the next US presidential election.

And they hope the fight over Obamacare will play in their favour.

Perhaps such talk sounds premature. In Australia, the eight-week 2016 double dissolution federal election campaign was considered interminable. But for the party that loses the White House, the campaign for the next election starts immediately.

Soul searching turns to star searching in the blink of an eye. That's especially true this go-round.

Mr Trump wasn't supposed to win. While his unpopularity is high in historical terms, Democrats fret because the Trump base has proved remarkably loyal and a sitting president has an advantage.

The Democrats' first task is to win back seats in Congress in the 2018 midterm elections.

But behind the scenes, would-be Democratic presidential candidates are already jockeying for position to lead the ticket in 2020.

At this early stage, wannabes generally play coy. But it's widely assumed Senator Elizabeth Warren of Massachusetts, Vermont Senator and former presidential candidate Bernie Sanders, and Senator Cory Booker from New Jersey are interested.

Former vice-president Joe Biden also rates a mention. And there are others.

Tell-tale clues to presidential ambitions include what's said and not said, where this occurs, how surrogates respond when quizzed, and writing a book.

Which is why Beltway insiders listened very carefully to Hillary Clinton's high-profile interview with CNN's Christiane Amanpour this week.

Could she, would she, consider running again?

Will Clinton run in 2020?

Sorry, this video has expired Hillary Clinton reflects on her election campaign and Donald Trump's negotiating methods. (Image: Reuters/Brendan McDermid)

There's an old rule in politics. Never say never.

After her bombshell loss, Mrs Clinton took herself off to the woods. Literally. She disappeared from view, save for rare sightings of her hiking near her home in Chappaqua, New York or going to dinner or a movie.

But this week, the former Democratic candidate for president was front and centre at a Women for Women International event in New York.

She said she took "absolute personal responsibility" for the loss.

She then made it abundantly clear she blames the loss on Russian intervention in the election and FBI Director James Comey's decision to reopen an investigation into her emails just days before voters went to the polls.

"If the election had been on October 27, I would be your president."

Mr Trump fired back by Twitter. He called Mr Comey "the best thing that ever happened to Hillary Clinton in that he gave her a free pass for many bad deeds!"

In another tweet, he said the "Trump/Russia story was an excuse used by the Democrats as justification for losing the election. Perhaps Trump just ran a great campaign?"

Testifying before the Senate Judiciary Committee on Wednesday, Mr Comey was in the hot seat.

He told Congress he felt "vaguely nauseous" that his decision to speak publicly might have altered the outcome of the election, but "I think I've done the right thing at each turn".

Democrats saw a double standard. They grilled Mr Comey about why he went public regarding a batch of Clinton emails but remained mute about the FBI's investigation into whether there had been links between Trump associates and Russian officials during the 2016 campaign.

Mr Comey made it clear the FBI investigation into the exact nature of Russian interference in the US election isn't over.

Four congressional committees are also looking into the matter.

The timing of Mrs Clinton's re-emergence on the national stage is noteworthy.

Any losing candidate needs a narrative to explain what happened.

The newly-released book Shattered, by political reporters Jonathan Allen and Amie Parnes, points to epic campaign in-fighting.

It faults Mrs Clinton for being unable to articulate a clear vision and that tone-deaf comment about "deplorables."

But the ongoing investigation into Russian interference makes it clear there was more.

It removes some of the blame and stigma from a failed candidacy.

Mrs Clinton's interview with Amanpour can be read as the first careful step to rehabilitation after a crushing loss.

But what's next? If a candidate got mugged, does she deserve another chance?

What's next for Clinton?

Here's what we know: Mrs Clinton is working on two books. The first is an updated picture book of It Takes a Village. The second is a collection of essays with inspirational quotes and advice.

What are her surrogates saying? In an appearance on CBS This Morning last month, Chelsea Clinton was asked point blank if her mother might run again. She replied, "Oh I have no idea ... I don't think so".

Please note that the former first daughter did NOT say any of the following: ARE YOU KIDDING? NO WAY. HELL WILL FREEZE OVER FIRST! DO YOU THINK SHE IS CRAZY?

She mentioned her mother's book projects and work to help families and said, "She's focused, thankfully, on her grandchildren".

Dear me. Hillary Clinton said that before, didn't she?

In politics, there are ways to slam the door shut. Mrs Clinton hasn't done that. But after decades of a very public ambition to be the first woman president of the United States, she seems to be shifting gears.

In a recent interview with New York Times columnist Nicholas Kristof, she shuddered when asked if she would run for president again.

Most Democrats feel the same way. They believe they were robbed. But Mrs Clinton lost and they want to move on.

While many Americans want to see a woman become president and believe misogyny was a factor in Mrs Clinton's defeat, don't expect to see Hillary or Chelsea Clinton on the Democratic ticket next time.

Both major US parties have been burned by dynasties. After Mr Trump's upset win, outsiders are in vogue.

But perhaps most importantly, a detailed analysis of the 2016 race showed that many people who voted for former president Barack Obama switched parties to vote for Mr Trump.

Voters are fickle these days and party loyalty becoming a thing of the past.

Democrats will want to find a candidate who can siphon off some of those Trump voters and yet appeal to what's left of their base.

It is famously said that hindsight is 2020. Democrats must examine the rear view mirror closely as they look to the future and pick their candidate for 2020.

