As a general rule, a president’s party tends to lose seats during midterm elections, and the losses are often steepest during the midterm elections of a president’s first term. In the last 100 years, a new president’s party has lost an average of 23 seats in the House of Representatives.

But if there’s one thing we’ve learned in recent years, it’s that the old political rules don’t always apply to President Trump. First as a candidate and now as president, Trump has consistently proved the media and pollsters wrong, rewriting the presidential rulebook along the way.

No, I’m not predicting that Republicans will pick up seats in Congress. But if midterm elections are referendums on the sitting president, we may want to rethink how voters will respond at the ballot box this year.

[Also read: Democrats closing gap in key Senate races as late polls defy forecasts]

When presidents are punished at the midterm ballot box, it’s usually for failing to deliver on their campaign promises.

The last first-term president to face a midterm election, former President Barack Obama in 2010, received what Obama accurately called a "shellacking" at the ballot box. Democrats lost a net of 63 seats in the House of Representatives, relinquishing the majority. They also lost six Senate seats.

There were several reasons for the backlash. Perhaps most important was the betrayal many Obama voters felt. Obama had campaigned as a bridge builder who would unite the country after a period of deep division. But he turned out to be a conventional liberal.

Instead of advancing a bipartisan agenda, he immediately got to work “fundamentally transforming” the country by passing a sweeping liberal agenda with almost no Republican support. He inflicted government-run healthcare on a public that didn't want it and imposed a massive, 800-page regulatory reform law (Dodd-Frank) based on the mistaken belief that the Great Recession was caused by unregulated financial markets.

Like so many presidents before him, Obama campaigned as one thing and governed as another. Millions of Republicans and independents voted for Obama believing his promises of post-partisanship. When he didn’t follow through on those promises, they felt duped, making the “shellacking” inevitable.

Obama isn't alone. George H.W. Bush won the presidency in 1988 thanks in no small measure to his “no new taxes” pledge. He famously broke that promise, spurring a backlash at the polls that led to Democratic gains in both houses of Congress two years later and to Bush losing his bid for re-election in 1992.

Former President Bill Clinton’s attempts to impose a massive, top-down, government-run healthcare plan shortly after entering the White House led to the 1994 Republican Revolution. Republicans’ 54-seat net gain allowed them to recapture the House for the first time in 40 years.

Trump has been a very different kind of president. As a candidate, he was very clear about what he wanted to accomplish. Pundits often accused Trump of being erratic and undisciplined on the campaign trail. But he demonstrated uncommon discipline in delivering his message clearly and consistently.

Trump promised to cut taxes, slash government regulations and revive the economy. He pledged to nominate conservative judges, secure the border, pressure allies to contribute their fair share to NATO and withdraw from the Paris climate accord. He vowed to impose tariffs on aluminum and steel and renegotiate trade deals that were unfair to America’s workers. He vowed to move the U.S. embassy in Israel to Jerusalem, crush the Islamic State, and institute a temporary travel ban from unstable countries. The list goes on.

Trump has kept all those promises and more. The economy is the strongest it’s ever been, and America is further away from nuclear conflict with North Korea than we were on the day Trump took office.

Even on the items Trump has failed to accomplish (full Obamacare repeal and the border wall, for instance) he has at least tried and vowed to revisit them after the midterms.

Trump may exaggerate his poll numbers and crowd sizes. But when it comes to the things voters ultimately care about (whether or not a president fulfills his campaign promises) Trump has been the picture of truthfulness – which is why Trump’s approval rating recently reached the highest point in his presidency, including a record-high 88 percent approval rating among Republicans.

If past is precedent, Republicans could lose a significant number of seats on Tuesday. But it would be a mistake to assume that a “blue wave” will descend over the country.

The midterms will be about a million things, many of which have nothing to do with the president. But to the extent that they are a referendum on Trump’s record of keeping his campaign promises, we could be in for another precedent-busting performance.

Gary Bauer is a contributor to the Washington Examiner's Beltway Confidential blog. He is president of American Values and chairman of Campaign for Working Families. He ran for the Republican presidential nomination in 2000.