WASHINGTON — January will mark the beginning of a cavalcade of Democratic presidential hopefuls who are preparing to officially launch their campaigns early in the new year, according to multiple advisers and aides working for the prospective candidates.

Running for president has become a two-year endeavor, and, even though everyone says they hate it, candidates invariably get sucked into the presidential primary-industrial complex and rush to Iowa and New Hampshire as quickly as possible, lest they get left behind.

The calculus that goes into that decision turns out to be pretty simple and comes down to one thing above all else: money. And lots of it.

Seeking the White House has never been more expensive, and some veteran Democrats estimate a candidate will need to raise $10 million to $15 million in the first quarter of 2019, and at least $50 million during the full year, to be seriously competitive once voters start actually casting ballots in early 2020.

Trump's re-election campaign and affiliated GOP groups have already raised more than $100 million, while the Republican National Committee has raised tens of millions more.

Many potential Democratic candidates have circled January or early February on their calendars as the ideal launch window — early enough to try to raise an impressive amount of money in the first quarter of the year without stepping on November's midterm elections.

"I have an announcement on Jan. 12," Julian Castro, the former Obama Housing secretary, who is publicly exploring a presidential campaign, said on NBC's "Meet the Press" on Sunday.

"I know I have to make up my mind, and I have to do it by January," former Vice President Joe Biden said earlier this year on CNN.

"Anything I might do politically is probably not something that I'll be making any news about before January," Mayor Pete Buttieig of South Bend, Indiana, said this month after announcing he won't run for re-election, potentially to make a bid for the presidency.

Meanwhile, Democratic Sens. Elizabeth Warren of Massachusetts, Cory Booker of New Jersey and Kamala Harris of California are all also quietly preparing for potential campaign launches in early 2019, people close to them have said.

That follows roughly the same timing as Hillary Clinton and Barack Obama, who started their famous 2008 primary brawl in late January and early February 2007, respectively.

What's so special about January?

As December winds to a close, no new names have come up, even though November and December were wide open for the taking. Whatever advantages other timelines may offer, the financial calendar seems to trump them.

January is likely to be crowded because it comes at the start of a financial quarter, which gives candidates the maximum amount of time to raise money before announcing their first fundraising haul at the end of the quarter in March. Extra days mean more swank campaign fundraisers, dialing-for-dollars calls, and more email solicitations to grassroots contributors who chip in just a few dollars at a time.

Presidential campaigns’ first fundraising reports to the Federal Election Commission are scrutinized like report cards by the media, rivals and opinion-leading party leaders, labor union heads and elected officials, as they decide whom to support.

A lack of early fundraising strength can be a death knell for a candidate since donors both large and small look to bet on a winning candidate and are quick to drop perceived losers.

Money isn't everything in politics, but it's a lot. And a strong first quarter fundraising haul is one of the surest ways to demonstrate viability and strength, not just in the primary, but in the general election against Trump.

Plenty of candidates run for president when they have little chance of winning, but none do so once they run out of money. "We simply didn't have the resources to compete going forward," Rick Santorum explained of his decision to quit the 2012 Republican race.

Unexpectedly strong fundraising has helped underdog candidates like Obama in 2008 and Bernie Sanders in 2016 be taken seriously and vault to the top of the field.

For Democrats in 2020, the financial demands will be even higher and the need to raise funds even more urgent since large, expensive states like California and Texas have moved their primaries to just after the Iowa caucuses and the New Hampshire, Nevada and South Carolina primaries. That makes California and Texas more important, creating incentives for candidates to invest more heavily and earlier there than they would have in previous years.

The Democratic National Committee has also moved up its national convention and will start conducting debates as early as June 2019.

"It's going to be a very condensed," Los Angeles Mayor Eric Garcetti, who is considering a 2020 bid, said of the primary process at a Bloomberg event this month. "There's going to be, I think, a very different dynamic this time around."