Tom Steyer

The Democratic presidential nominating contest now heads into a critical phase.

The candidates have so far stood for elections in two of the whitest states in the country, Iowa and New Hampshire. But Nevada and South Carolina — the next two states to vote — will provide far more diverse electorates.

There are now no more official debates before Democrats begin voting.

Tuesday night's debate was the last before the Iowa caucuses on Feb. 3, and it featured six of the 12 remaining candidates — the top four of whom polls show to be neck and neck.

Democratic primary voters got a substantive debate in which the candidates clashed over what it means to be commander in chief, gender politics and, of course, health care.

Here are four takeaways from Tuesday night's debate:

Update at 3:30 p.m. ET

We're up to the seventh debate, and down to six candidates.

The leading Democratic presidential candidates return to the debate stage Tuesday at 9 p.m. ET — this time in Iowa, which hosts the first-in-the-nation caucuses in less than three weeks.

Updated at 12:25 p.m. ET

Viewers tuning in for the latest Democratic presidential candidates' debate Tuesday night may sense something missing in Des Moines.

The Democratic stage will be the smallest yet for next Tuesday's Iowa debate, with just six candidates set to qualify.

Billionaire activist Tom Steyer on Thursday likely became the latest candidate to qualify after two Fox News polls from Nevada and South Carolina showed him in the double digits. Steyer has been spending millions of dollars in early states to boost his chances.

Michael Bloomberg, the billionaire former mayor of New York City, entered the Democratic presidential primary a month ago. He's already spent more than $100 million on advertising.

Bloomberg and Tom Steyer, another billionaire in the Democratic contest, have in total spent about $200 million so far, according to Advertising Analytics, a firm that tracks campaign ad expenditures.

Hedge fund billionaire and environmental activist Tom Steyer is taking a campaign tour through Ohio, more than a week after launching a bid for the Democratic presidential nomination.

Tom Steyer, a California billionaire hedge fund manager and environmental activist, is the latest to jump into the Democratic presidential race.

Steyer has gained national attention with his quest to impeach President Trump. Steyer had previously said in January that he would not be running for president and would instead run a $40 million ad campaign to push for President Trump's impeachment.