U.S. Senator Cory Booker (D-NJ) seen speaking during the Open Markets Institute's conference, A Right to Compete: Are Monopolies Crushing Entrepreneurship in Washington, DC.

Sen. Cory Booker, D-N.J., has started consulting with two top Iowa presidential campaign strategists – one who worked with Hillary Clinton and another who worked with former President Barack Obama – as he contemplates a run for the White House in 2020, CNBC has learned.

These early conversations with top-tier consultants in Iowa, where the major parties hold their first contests of the presidential election season, are the latest signs Booker could be preparing to launch a campaign. He has said publicly that he is thinking about running for president.

The Iowa Caucuses represent an early test for candidates on the road to their party's nomination for president. Clinton, the eventual Democratic nominee, edged out Sen. Bernie Sanders, I-Vt., by less than a percentage point in the 2016 caucuses. Eventual GOP nominee and President Donald Trump, on the other hand, lost the Republican Iowa Caucus to Sen. Ted Cruz of Texas.

It appears that Booker is looking to get a head start on the rest of the potential Democratic 2020 field in the crucial state. He has held discussions with Matt Paul, who led Clinton's Iowa Caucus operation in 2016, according to three people with direct knowledge of the matter. Paul currently works as senior vice president for consulting firm Cornerstone Government Affairs.

Paul and Booker held one of their earliest discussions in October, during the Iowa Democratic Party's annual fall gala in Des Moines in October. At the party, Paul, who is known as a "state ambassador" for Democrats considering a run for president, acted as an intermediary for Booker as he introduced him to dozens of political operatives and party activists, according to a person familiar with the discussions.

The two have stayed in touch since the party, discussing a variety of topics, including how Democrats win during the Iowa Caucuses as well as the potentially expansive field of potential Democratic presidential candidates in 2020, said two people familiar with the matter.

A person close to Booker emphasized that these conversations have been general in nature and that it is too early to say whether the New Jersey lawmaker will try to hire Paul as a consultant. Booker is also up for re-election to the Senate in 2020.

A spokesman for Booker declined to comment. Paul did not return repeated requests for comment.

Meanwhile, Jeff Link, Obama's deputy director for paid media and research during his 2008 run for the White House, said he has also been in touch with Booker. According to Link's website, he coordinated all paid media and polling in 25 states, including seven battleground states, for Obama's campaign that year. Obama turned heads early on in the 2008 campaign, defeating Clinton in the Iowa Caucuses.

Booker and Link also privately spoke at the gala, Link told CNBC in an interview. He said he has not heard from either Booker or his team since then. He noted, however, that his first meeting with the Democratic lawmaker at the party was an introduction. They also talked about the candidates Booker was backing at the time – and the rousing speech he gave that night.

"I thought he gave a great speech. He got the crowd really engaged and he did an excellent job there," Link said. "He would be a real factor if he has a go here in Iowa."

Booker's speech focused, in part, on a call to support women who run for office and those come forward with sexual assault allegations. The address came just hours after Democrats failed to block the nomination of Brett Kavanaugh to the Supreme Court. Kavanaugh, a former federal appeals judge in D.C., was accused of sexual assaulting a girl when they were both in high school more than three decades ago. He vehemently denied this allegation and others that surfaced. The Senate confirmed him to the top court along mostly partisan lines, 50 to 48.

"We're not defined by a president who does not believe women," Booker said in his speech. "We're gonna be defined when this state not only says that we believe women, but that we elect women!"

At least 100 women went on to win their individual House races during the midterm elections earlier this month.

Booker has made other moves that indicate he is seriously preparing to run for president.

Next month, he is reportedly set to a second trip to New Hampshire, which traditionally holds the first primary election of the campaign season. Politico recently reported that Booker has been reaching out to other potential consultants in that state as well as in South Carolina, another early primary state.

Recently polling puts Booker in the top 10 of preferred presidential candidates for Democratic voters. According to a Morning Consult/ Politico poll, Booker is ranked sixth among Democrats' preferences for their 2020 candidate, scoring 3 percent of the vote. California Sen. Kamala Harris, Massachusetts Sen. Elizabeth Warren, Texas Rep. Beto O'Rourke, former Vice President Joe Biden and Sanders rank ahead of Booker.

The survey of 733 Democratic voters took place online with a four-point margin of error.

Correction: This story was updated to reflect Beto O'Rourke's title.