If only 107,000 votes in three Rust Belt states had shifted to the left, Donald Trump would not be president. He received, after all, nearly three million fewer votes than Secretary of State Hillary Clinton, and was elected thanks to the technicalities of the U.S. electoral college.

A substantial body of American mainstream opinion also continues to believe that Russian intelligence, through covert electoral interference, significantly contributed to Trump's precarious 2016 electoral victory.

Since his inauguration in January 2017, Donald Trump has continued to be dogged by controversy. In contrast to every modern presidential candidate, he refused in 2016 to release his past tax returns and fought an extended, still-continuing legal battle to avoid doing so.

Similarly, Trump refused to divest his substantial business assets, with his sons continuing to run the prominent Trump Hotel, less than 500 meters from the White House, where foreign visitors frequently stay.

Trump has also been dogged by multiple sex scandals from his pre-presidential days, while his 2016 campaign manager, his first national security advisor and his personal attorney are all now in jail.

To top matters off, President Trump has been accused of withholding military aid from Ukraine, a major informal ally of the United States in its geopolitical struggles with Russia, to get the Ukrainians to provide incriminating evidence against his leading 2020 presidential campaign rival, former Vice President Joseph Biden.

Many Republicans vigorously dispute those charges, but they led in mid-December to the president's impeachment by the House of Representatives. This is only the third time in American history that a U.S. president has been formally impeached.

Despite all this controversy, Donald Trump's approval ratings have remained surprisingly strong. Not stratospheric, but remarkably strong considering the narrow margin of his election victory, and considering all that has happened since.

This past week, Trump's presidential approval ratings were around 45 percent, roughly the level when he was elected. Trump's ratings were significantly higher than those of House of Representatives Speaker Nancy Pelosi (38 percent) and Senate Majority Leader Mitch McConnell (26 percent).

Even more remarkably, Trump is more popular than President Barack Obama was at a comparable stage of his first term, just about to enter his re-election campaign year. Indeed, on December 10, 2011, Barack Obama's presidential job approval stood at 43.6 percent; eight years later, Donald Trump recorded 44.4 percent.

How has Donald Trump been able to retain such a remarkable degree of public support, despite the cloud of controversy that continually surrounds him?

Will this "Teflon capacity" translate into a resounding re-election victory next year? It is clearly too soon to judge the latter issue -- especially given the multiple controversies still surrounding Trump, as well as the state of political and economic conditions next year.

Yet it is not too soon to reflect on the remarkable "Teflon" character of Trump's presidency so far, and whether he can sustain it.

Four factors have been crucial in sustaining that support.

First, Trump has consistently had an important economic tailwind at his back. Even though his protectionist, tariff-oriented trade policies have complicated economic growth, Trump has presided over a remarkable period of sustained domestic prosperity, including a booming stock market -- the Dow Jones average has risen well over 20 percent this year. Tax cuts and low interest rates have encouraged both corporate profits and consumer spending while inhibiting deflationary appreciation of the dollar.

The liberal drift of the Democratic Party has arguably contributed to Trump's remarkably strong political showing. The party has appealed consistently to its increasingly diverse and liberal base, which has alienated many middle-of-the-road voters. This problem has been especially acute in the politically important Rust Belt and Appalachian states, and among working-class white men nationwide.

Trump's policy record has been decidedly mixed, incurring substantial criticism for his approach to European allies and Middle Eastern affairs, in particular. He has had some concrete, conspicuous recent policy successes, however, especially on Japan, China, and North America-related trade issues. These seem to have brought him enhanced support in important battleground states across the Midwest.

Trump's most formidable electoral asset, however, may well be his own aggressive, direct, and heretofore unprecedented political style.

He is omnipresent chronologically in the American news cycle, due to his unsettling habit of tweeting at all hours of the day and night.

He is also omnipresent geographically across the swing states and Republican parts of the nation, holding political rallies with his base supporters almost every week, or sometimes more. Trump is also extremely combative, retaliating rapidly to any criticism, and punishing defectors from his political line.

He has been especially combative in fighting impeachment proceedings, not so much by logic as by putting intense political pressure on the 31 House Democrats from districts he carried in 2016.

Donald Trump's methods raise major issues for the future of American democracy. He intimidates opponents and inhibits reasoned debate. He hires and fires with abandon, producing administrative uncertainty and often chaos within his administration.

Trump's foreign policy, such as it is, strikes at the heart of the multilateral structures, painstakingly fostered by his predecessors that have assured global security and prosperity for three generations.

Whatever their consequences for domestic policymaking and world affairs, Donald Trump's methods have so far been brutally effective, especially in keeping potential intra-party rivals within the Republican Party in line. He has an economic wind at his back, fostered by accommodative policies by the Fed.

As 2019 draws to a close, the era of Trump shows considerable prospects of continuing, impeachment proceedings notwithstanding. And therein lies a critical puzzle of American politics today.

(Kent E. Calder is director of the Reischauer Center for East Asian Studies at SAIS/Johns Hopkins University in Washington.)

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