“Basically all I've done is keep my promise,” President Trump told CPAC attendees after describing his plans to intensify the deportation of undocumented immigrants. At a press conference earlier this month, Trump scoffed, “Some people are so surprised that we are having strong borders. Well, that's what I've been talking about for a year and a half.”

Similar sentiment was expressed by Rep. Raul Labrador, who told the Idaho House the president is just “doing the things that he said he was going to do” and “"it should concern you all” that “people are reacting like this is something unusual or illegitimate.”

On the contrary, it should concern you all – whether you oppose or support Trump -- that he and his allies are trying to shut down debate over his policies by citing campaign rhetoric instead of defending his actions on the merits.

The mere fact that he said during the campaign he was going to do something in the abstract does not grant him, as president, immunity from scrutiny upon proposing or implementing a specific policy. Details matter. Execution matters. Fealty to the Constitution and the law matters.

The Founders designed a system of checks and balances. Presidential directives are supposed to receive rigorous debate and scrutiny from the legislative and judicial branches. Citizens retain their First Amendment right to be vocal and may press their representatives to thwart the president if they choose, because democracy doesn’t stop between Election Days. All of that is happening today, and it’s not “unusual or illegitimate.”

Such pushback should not surprise Republicans. They did not say Barack Obama was just doing what he said he would do regarding health care, Wall Street reform, taxes, climate change and immigration. They stormed town halls. They resisted in the Congress. And when that didn’t work, they petitioned the courts.

Republicans should also remember what can happen when you assert a mandate that isn’t really there. Upon winning re-election in 2004, President George W. Bush decreed, “I earned capital in this campaign, political capital, and now I intend to spend it.” He pledged to follow through on his campaign rhetoric and add private accounts to Social Security. Democrats, undaunted by Bush’s popular vote majority, scorched the plan as antithetical to Social Security’s premise. Public opinion quickly turned against the president’s plan. Given the certainty of a filibuster, the idea never came to a vote, and Bush’s political capital was sapped.

Bush couldn’t conjure a mandate after he had a popular-vote majority. Trump doesn’t even have that. And his immigration agenda fared worse in Election Day exit polls, with only 41 percent supporting a border wall, and 25 percent supporting deportation of undocumented workers. More recent polls peg border wall support below 40 percent, and similarly weak support for his deportation policy.

Yet he’s not putting forth an agenda that would expand his base of support. By saying don’t be “so surprised,” Trump is effectively telling the 54 percent of voters who didn’t back him that he’s only going to do what his most ardent supporters like. In other words: Blue America, get over it.

That should concern those who hope to see him re-elected.

Typically, presidents who win with pluralities or minority popular votes adjust their agendas to appeal to more voters. While it’s theoretically possible to thread a political needle twice, plenty of presidents shed support after four years of tough decision-making.

The best way to avoid that pitfall is to keep reaching out to new sets of voters. Bill Clinton, who initially only won 43 percent of the vote, successfully wooed fiscally responsible Ross Perot supporters by shelving his signature campaign proposal of a middle-class tax cut in favor of deficit reduction. Richard Nixon, another 43 percenter, eyed moderate voters when he created the Environmental Protection Agency and embraced affirmative action. Bush, who lost the popular vote in 2000, made a point of crafting bipartisan legislation on education and health care with liberal stalwart Sen. Ted Kennedy. All won more votes in their re-election bids.

The 46 percent understandably are thrilled that Trump is following through on much of his rhetoric. But trying to insulate Trump from the rigors of democracy, by arguing he doesn’t have to explain himself beyond regurgitating his campaign rhetoric, or moderate his policies to reflect the electorate, is a recipe for a short White House stay.