Some of the first moves of the 2020 presidential campaign are happening now, not in New Hampshire but on Capitol Hill. A group of Senate Democrats seem to be fighting to out-liberal one another, a bloc of House Democrats are taking a more centrist course, and some Senate Republicans may be positioning themselves for when President Trump is not the GOP’s nominee in 2024 — or even earlier.

There’s nothing new about members of Congress, particularly senators, preparing for presidential runs while also serving on Capitol Hill. John F. Kennedy did this. So did Hillary Clinton and John McCain. So did Rand Paul. What’s different heading into the 2020 cycle is that a fractured Democratic Party, a deeply unpopular, scandal-plagued president, and the country’s changing demographics and culture have already created a massive field of potential candidates that includes four female senators, two African-American senators, a bunch of House hopefuls and two senators from the sitting president’s own party. And that’s just the possible presidential hopefuls in Congress; we’re not even talking about the mayors, governors, former officeholders and celebrities who could decide to run.

Here’s the thing: All this unofficial early campaigning matters now because this presidential positioning had real effects in 2017 and is likely to have effects in 2018 as well. As Republicans try to maintain enough order to accomplish their legislative priorities, Democrats have to decide issues like whether they want to force a showdown with the president and Republicans over immigration, whether to make the potential impeachment of Trump a major issue in the midterm elections, and how to handle new charges of sexual misconduct against lawmakers. The presidential wannabes are likely to have a major say in those decisions.

The Senate Democrats

Six Senate Democrats (New Jersey’s Cory Booker, New York’s Kirsten Gillibrand, California’s Kamala Harris, Minnesota’s Amy Klobuchar, Oregon’s Jeff Merkley and Massachusetts’ Elizabeth Warren), plus semi-Democrat Bernie Sanders (he’s technically an independent, but he ran for the Democratic nomination in 2016 and is a member of the Senate Democratic Caucus), are rumored to be considering presidential bids. Of this group, all but Warren have taken some of the steps that I described early this year as signs that someone is considering a presidential run, including attending a political event in Iowa (Klobuchar, Merkley, Sanders), campaigning for Democrats in key U.S. Senate or gubernatorial races (Booker, Harris), and allowing a major magazine to interview them for a profile piece (Gillibrand).

Here’s another clue that these members are thinking about running for president: Most Democrats on Capitol Hill strongly oppose Trump, but the senators who have the lowest ratings on the FiveThirtyEight Trump score (meaning that they vote against the president’s position most often) are, in order of highest rate of opposition, Gillibrand, Warren, Merkley, Booker, Sanders, Ed Markey and Harris. The New York senator votes with the president just 9 percent of the time. (There is no indication that Markey, the other Democratic senator from Massachusetts, is likely to run for president in 2020.)

Democratic senators with the lowest Trump scores How often a senator votes in line with Trump’s position MEMBER STATE TRUMP MARGIN PREDICTED SCORE TRUMP SCORE Kirsten E. Gillibrand NY -22.5 23.8% 8.9% Elizabeth Warren MA -27.2 21.1 10.7 Jeff Merkley OR -11.0 34.7 12.5 Cory A. Booker NJ -14.1 30.9 14.3 Bernard Sanders VT -26.4 21.5 14.3 Edward J. Markey MA -27.2 21.5 14.5 Kamala D. Harris CA -30.1 19.7 16.1 Ron Wyden OR -11.0 34.7 17.9 Richard Blumenthal CT -13.6 31.3 20.0 Tammy Baldwin WI 0.8 55.6 21.4 Chris Van Hollen MD -26.4 21.9 21.8 Richard J. Durbin IL -17.1 27.1 22.2 Charles E. Schumer NY -22.5 23.8 23.2 Patty Murray WA -15.5 29.5 23.2 Jack Reed RI -15.5 29.5 23.2 Sheldon Whitehouse RI -15.5 29.5 23.2 Tom Udall NM -8.2 38.7 23.2 Robert Menendez NJ -14.1 28.5 24.1 Al Franken MN -1.5 49.4 24.1 Mazie K. Hirono HI -32.2 18.8 25.0 Tammy Duckworth IL -17.1 28.0 25.0 Martin Heinrich NM -8.2 38.7 25.0 Brian Schatz HI -32.2 18.8 26.8 Patrick J. Leahy VT -26.4 21.5 26.8 Benjamin L. Cardin MD -26.4 21.5 26.8 Maria Cantwell WA -15.5 29.5 26.8 Christopher Murphy CT -13.6 31.3 27.3 Robert P. Casey Jr. PA 0.7 55.5 28.6 Michael F. Bennet CO -4.9 44.3 30.4 Amy Klobuchar MN -1.5 50.9 30.4 Debbie Stabenow MI 0.2 54.5 30.4 Sherrod Brown OH 8.1 70.1 30.4 Dianne Feinstein CA -30.1 20.0 30.9 Christopher A. Coons DE -11.4 34.5 30.9 Gary C. Peters MI 0.2 54.4 30.9 Thomas R. Carper DE -11.4 34.1 32.1 Margaret Wood Hassan NH -0.4 53.3 32.1 Jeanne Shaheen NH -0.4 53.3 32.1 Tim Kaine VA -5.3 43.5 33.9 Catherine Cortez Masto NV -2.4 49.1 33.9 Bill Nelson FL 1.2 56.5 37.5 Jon Tester MT 20.4 85.8 39.3 Mark R. Warner VA -5.3 43.5 42.9 Claire McCaskill MO 18.6 84.2 43.6 Angus S. King Jr. ME -3.0 48.0 44.6 Joe Donnelly IN 19.2 84.5 47.3 Heidi Heitkamp ND 35.7 92.5 50.0 Joe Manchin III WV 42.2 93.2 53.6 Includes independent senators who caucus with the Democrats.

This group is perhaps the most important bloc of 2020 contenders — because they make the biggest difference in terms of what is happening on Capitol Hill right now. In taking steps that might appeal to the Democratic base for future presidential runs, they are pushing one another and their congressional colleagues toward the left and redefining Democratic stances in both Congress and the broader party.

In August, when Sanders floated his idea of introducing a bill that would expand Medicare to cover health care for all Americans, Harris was the first of his colleagues to say that she would support the legislation. By the time Sanders formally introduced the bill in September, 16 of the 48 members of the Democratic caucus had signed on as co-sponsors of the legislation, including Booker, Gillibrand, Merkley, Warren and Harris.

In October, Harris was one of the first Democrats to say that she would vote against any government funding bill that did not include some kind of provision to replace the Obama-era Deferred Action for Childhood Arrivals program — which removes the threat of immediate deportation for young, undocumented immigrants who were brought to this country by their parents — that Trump ordered to wind down last fall. When the Senate voted on a temporary funding bill early last month that did not include any help for these immigrants, eight Democrats voted no: Markey and Hawaii Sen. Mazie Hirono, as well as Booker, Gillibrand, Harris, Merkley, Sanders and Warren.

Liberal activists were furious that more members didn’t join in, calling on Democrats to force a government shutdown if Congress did not move to replace DACA. In a subsequent temporary spending bill that also did not address DACA, 30 Senate Democrats voted no — not enough to force a shutdown, but a clear shift from the previous vote.

Gillibrand, for her part, was the first Democrat to call for her party colleague Minnesota Sen. Al Franken to resign amid allegations of sexual misconduct, leading 31 fellow Democrats — including Booker, Harris, Merkley, Sanders and Warren — to also push for him to step down.

Gillibrand’s criticism of Franken and recent suggestion that Bill Clinton should have resigned as president because of his affair with Monica Lewinsky are laying the groundwork for a campaign that features issues of gender and power, which could be a major potential selling point in a Democratic Party where the majority of voters are women.

Harris and Booker, meanwhile, are advocating for criminal justice reforms that might appeal to both people of color and white Democrats who are liberal on racial issues. Harris is pushing legislation to change the bail system, arguing that it discriminates against black and Latino defendants who often can’t afford to make bail and so remain in jail as they wait for their trials. Booker wants to legalize marijuana at the federal level and provide incentives for states to do the same.

If you’re Schumer, the leader of the Senate Democrats, or House Democratic leader Nancy Pelosi, these members and their ambitions may scare you. They seem to be trying to match one another’s liberal stances, regardless of what that might mean for the party at midterms.

So if, say, Warren suggests impeachment should be on the table, Sanders and Booker might echo that view a few days later, forcing party leaders to deal with some of their highest-profile members taking a stance that the base already agrees with but that might not be the safest position for the party as a whole to take in its efforts to win control of Congress.

This kind of move could be a mistake — or a misunderstanding of where the Democratic electorate will be in 2019 and 2020. In 2013, Florida’s Marco Rubio was a key architect of an immigration bill that included a path to citizenship for undocumented immigrants. At the time, Rubio’s embrace of that bill looked savvy, as he positioned himself as someone who could work across party lines and appeal to Latino voters. You know how that turned out.

Sanders’s Medicare-for-all proposal, for instance, is hardly guaranteed to be a winning idea in either the primaries or the general election, leaving those who embrace it vulnerable to being attacked by more moderate rivals who argue the approach is too expensive and impractical. Even if many Democratic senators sign on to that cause, there a number of possible Democratic candidates outside the Senate, like Montana Gov. Steve Bullock, who have not endorsed Medicare for all and could argue against the idea. And Gillibrand is already facing something of a backlash for her part in pushing Franken, who was beloved by many liberals, out of the Senate.

That leaves space for some potential candidates to push back against the leftward march. One of the Senate Democrats who is taking steps to run for president has already done just that: Amy Klobuchar. The Minnesotan did not cosponsor the Sanders-written Medicare-for-all legislation; she voted in support of a government funding bill that did not include a DACA-style provision; and she backs the Trump position more often than the majority of Senate Democrats. She also did not call for Franken to resign, although that may have been out of respect for her home-state colleague.

There are three potential explanations here. First, she could simply be more ideologically conservative than her colleagues, although she does not have a reputation for being particularly centrist. Secondly, Klobuchar — like Gillibrand, Sanders and Warren — is up for re-election in 2018. She’s running in a purple state where Hillary Clinton won by only 1.5 percentage points in 2016, a much smaller margin than Clinton’s wins in New York, Massachusetts and Vermont; Klobuchar may need to appear more moderate to keep her current job. Third, Klobuchar might be running in 2020, but she may be planning to position herself as a more moderate alternative to her colleagues.

The House Democrats

Speaking of more moderate, a number of House Democrats are also rumored to be planning presidential runs, and some of them, like Massachusetts’ Seth Moulton and Ohio’s Tim Ryan, have visited the early-primary states. Maryland’s John Delaney has already announced his 2020 candidacy, which has to be one of the earliest entrances to a presidential race in recent memory. If any of these men actually run, it will be a long-shot candidacy: Only one sitting House member (James Garfield in 1880) has ever been elected president, compared to three sitting senators (Warren G. Harding, John F. Kennedy and Barack Obama).

It’s worth noting that the field of candidates coming from the Senate includes four women and two African-Americans, while these House hopefuls are three white men. I suspect that these representatives, if they run, will pitch themselves as able to appeal to white working-class voters who backed Trump in 2016 after previously voting for Obama. And they are not particularly anti-Trump among House Democrats, as measured by Trump scores, which would fit with a potential strategy of running to the center of the 2020 Democratic field.

But the party’s fiercely-anti-Trump leftward movement has affected these potential candidates, too. Ryan actually signed onto a Medicare-for-all bill, while Moulton voted against a motion to stop consideration of a proposal that would start impeachment proceedings against Trump, meaning he was in effect one of just 58 House Democrats who wanted to consider an attempt to remove the president. (The motion succeeded and the proposal was tabled.)

The Republicans

Two Republican senators are making their own presidential moves: Arkansas’ Tom Cotton (who made an Iowa visit and was interviewed for a profile in The New Yorker) and Nebraska’s Ben Sasse (two Iowa visits). For now, neither of these men seem like they are laying the groundwork for a primary challenge to Trump. (Ohio’s John Kasich seems a more likely candidate for that path.) Instead, I think they are setting themselves up as potential candidates if for some reason Trump doesn’t run for re-election.

In the Senate, they are largely voting the Trump/Republican Party position on issues — close to 90 percent for both men. While Sasse’s votes and legislation in the Senate are unremarkable, though, he is known for attacking Trump’s tone — particularly the president’s tweets. Sasse seems to be aiming to be the successful version of the Rubio 2016 campaign: Establishment conservatism delivered with a smile.

Cotton, meanwhile, has allied strongly with Trump. He has introduced a bill that would lower the number of legal immigrants and refugees eligible to enter the United States each year; the legislation has gone nowhere on Capitol Hill, but Trump has embraced it. Cotton has also aligned himself with Trump’s positions on national security issues, like trying to limit the U.S. role in the Iran nuclear agreement negotiated by the Obama administration. Cotton seems to be positioning himself for the future as a candidate who’s Trump-like on policy (skeptical of international agreements and immigration) but who has a more senatorial manner.

Trump admires Cotton enough that there are rumors that the president would like him to leave the Senate and serve as head of the CIA. The Arkansas senator has to decide if leaving the Hill and serving the president will enhance his resume — or hurt him in a presidential run that he could be making happen as early as 2020.

I should emphasize that I suspect some of the 12 members of Congress I mentioned as possible candidates here will not end up running for president in 2020 — and there are many people outside of Congress who are likely to run, particularly on the Democratic side.

But for now, they are part of a presidential selection process that never really ends. In 2018, it will be going hot and heavy, even if many of those who are setting themselves up to run never actually set foot in Iowa or New Hampshire.