President Donald Trump has two major advantages politically in 2020 presidential election over former Vice President Joe Biden: incumbency and enthusiasm.

The first is easy enough to understand. As the incumbent, President Trump has all the trappings of the head of state. He can do press conferences in the Rose Garden or the White House briefing room, meet with foreign leaders and dignitaries and address the nation in front of Congress or from the Oval Office. And after more than three years in office, the American people have a certain level of comfort with him.

Historically, incumbency has proven to be a major advantage in terms of electoral outcomes. The question for first-term presidents like Trump is whether or not voters think it is time for a change.

If you go back to the early history of the U.S., sitting presidents who have stood for re-election have won about 70 percent of the time, although until the 1800s, state legislatures generally chose electors.

Since 1948, incumbent first-term presidents have a 73 percent re-election rate in their first terms. Harry Truman won in 1948, Dwight Eisenhower was re-elected in 1956, Lyndon Johnson won John Kennedy’s second term in 1964, Richard Nixon was re-elected in 1972, Gerald Ford was ousted in 1976, Jimmy Carter was ousted in 1980, Ronald Reagan was re-elected in 1984, George H.W. Bush was ousted in 1992, Bill Clinton was re-elected in 1996, George W. Bush was re-elected in 2004 and Barack Obama was re-elected in 2012.

However, that number rises to 88 percent if one considers only cases of incumbent parties in their first term in the White House for reelection. This eliminates the Harry Truman first term which was really Franklin Roosevelt’s fourth term, George H.W. Bush term which was really the third Reagan term as well as Gerald Ford term which was Nixon’s second term.

The idea here is that the incumbency advantage is linked to the party in power for more than the individual, and that the longer a party remains in power after one term, enthusiasm wanes and the more vulnerable the party is to being ousted.

Which brings us to Trump’s second advantage in 2020: enthusiasm. In a June poll by Economist/YouGov, 68 percent of Trump supporters say they are enthusiastic about voting for him versus only 31 percent of Biden supporters who say they are enthusiastic.

49 percent of Biden voters say they merely satisfied but not enthusiastic, 15 percent say dissatisfied but not upset and 3 percent say they are upset. Whereas, with Trump, just 26 say they are satisfied but not enthusiastic, 5 percent say dissatisfied but not upset and 2 percent say they are upset.

In the same poll, among Biden supporters, only 35 percent say they are voting for Biden, whereas 62 percent say they are voting against Trump. For Trump supporters, 81 percent say they are voting for Trump, and just 18 percent say they are voting against Biden.

In April, a similar poll by HuffPost/YouGov found that Republicans and Republican-leaners were more enthusiastic about voting: 71 percent versus 57 percent for Democrats and Democrat leaners. 82 percent to 72 percent on very motivated to vote. And 90 percent to 82 percent very likely to vote.

In the same poll, Republican and Republican-leaners were slightly more inclined to follow election news more closely 48 percent to 46 percent.

It could be considered akin to a playoff phenomenon, where when major sports leagues get to the playoffs, television ratings plummet when your favorite team gets eliminated. Similarly, in politics when your preferred candidate wins an election, you are more likely to stay tuned into what’s going, watch the State of the Union Address and so forth.

The same can be said of primaries. Tying these two themes of incumbency and enthusiasm together is primarymodel.com by Stony Brook University Professor Helmut Norpoth  whose electoral model correctly predicted Trump would win in 2016 when all the polls said he wouldn’t.

As for 2020, Norpoth is once again forecasting Trump will win: “The Primary Model gives President Trump a 91 percent chance of winning a likely match-up with Democrat Joe Biden in November, based on primary performance in New Hampshire and South Carolina, plus the first-term electoral benefit. Trump would get 362 electoral votes, Biden 176.”

The major factor is how a candidate performs in political primaries plus which type of election cycle (first-term, second-term, third-term and so forth) the incumbent party is in, predicting the outcome. According to Norpoth, “It is a statistical model that relies on presidential primaries and an election cycle as predictors of the vote in the general election. This year the model has been calibrated to predict the Electoral College vote. Winning the early primaries is a major key for electoral victory in November.”

Which may be why Biden is in trouble this year, since early primaries gauge enthusiasm among party voters, and Biden’s was lacking: “On the Democratic side, Joe Biden and Bernie Sanders split the primaries in New Hampshire and South Carolina while Trump handily won the Republican Primary in New Hampshire (the GOP primary in South Carolina was cancelled this year).”

The cycle favors Trump, too, per Nortpoth, “What favors Trump in 2020 as well is the cycle of presidential elections operating for nearly 200 years, as illustrated by the snapshot since 1960. After one term in the White House the incumbent party is favored to win re-election unlike the situation when it has held office for two or more terms.”

Going back, the primary model correctly predicts the winner in 25 out of 27 presidential races going back to 1912 when political primaries were introduced.

The primary model says if the President’s political base stays on board and remains enthusiastic, then the incumbent will be able to win over those on the other side who are unsatisfied with the challenger, or simply encourage them to stay home in November.

So headed to the convention season, some key things to watch in polls are not necessarily the head-to-head matchups — although it is telling that in many polls Biden does not get above 50 percent (he averages 49.6 percent on Realclearpolitics.com) and in 2016 polls understated Trump’s support by several percentage points — but how Trump is doing specifically among Republicans and Republican-leaners.

With solid support from him base, on that count, so far, this election is Trump’s to lose.

Robert Romano is the Vice President of Public Policy at Americans for Limited Government.