Jeffrey Sachs is a professor and director of the Center for Sustainable Development at Columbia University . The opinions expressed in this commentary are those of the author; view more opinion articles on CNN.

(CNN) Congress should launch impeachment proceedings against Donald Trump for welcoming Russian interference in the 2016 election and trying to obstruct the Mueller investigation. Trump's high crimes and misdemeanors stare us in the face, and each day he remains in power is a day closer to the collapse of the rule of law.

Russian President Vladimir Putin unleashed his security apparatus to hack DNC emails and launched a disinformation campaign to troll the elections through Facebook and other means, according to Mueller's report . While Mueller did not find conclusive evidence that members of the Trump campaign conspired with the Russian government on the hacking and disinformation campaign, they knew that Russia offered assistance and "expected [the Trump campaign] would benefit electorally from information stolen and released through Russian efforts."

The hacking and social media campaigns "coincided with a series of contacts between Trump campaign officials and individuals with ties to the Russian government," according to the Mueller report , which includes a lengthy list of these contacts. Campaign chairman Paul Manafort, for example, shared internal polling data with a Ukrainian business associate with links to Russian intelligence, and discussed his strategy to win votes in the Midwest.

And when the US intelligence community assessed Russia meddled in the US elections, Trump took Putin's side and refused to

The second motivation was at least as pertinent. Trump's greed appears to match or exceed his lust for power. During the 2016 campaign, Trump was trying to secure a lucrative Moscow Trump Tower real estate deal. For that to succeed, Trump needed Putin's blessing. Trump's allies reportedly even floated the idea of giving Putin a $50 million luxury apartment in the Moscow Trump Tower, which may have violated the US Foreign Corrupt Practices Act

After the election, Trump repeatedly tried to shut down, curtail or limit Robert Mueller's investigation into Russia's illegal actions. The second half of the Mueller Report spells out many instances in which the President tried to undermine the investigation, which only failed because Trump's staff failed to carry out his orders

The Mueller investigation ultimately uncovered three devastating facts. The first, of course, was the extent of Russia's election interference and the Trump campaign's welcoming of that interference -- a double whammy that delegitimizes Trump's election victory. The second was Trump's brazen Russian business proposal during the campaign. The third included various financial dealings, including the hush money payment made to Stormy Daniels.

Trump poses a serious threat to this country. He tries to govern by one-man decree, declares phony emergencies to crack down on immigration, resists Congressional oversight and courts tyrants abroad.

Cautious Democratic leaders are reluctant to launch impeachment proceedings knowing that a conviction in a Republican Senate is currently against the odds, but they should recognize three overarching issues. First, as a matter of duty, they cannot shrug off rampant lawlessness without empowering thuggery in the future. Second, they can launch impeachment investigations now without deciding yet on whether to move to a vote, during which they and the public will gain information. Third, Trump's conviction by the Senate, or his resignation, remain plausible outcomes. During Watergate, public opinion was divided, even on the issue of Nixon's resignation, but the truth prevailed.

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Trump recklessly welcomed Russian interference in the 2016 election for political gain while he was pursuing personal business interests in Russia, and those actions, together with his brazen attempts to obstruct Mueller's investigation, surely constitute high crimes and misdemeanors justifying the launch of impeachment hearings. According to Mueller's findings, Trump has egregiously undermined the rule of law and bid US officials to do the same. Congress now must defend the Constitution and initiate impeachment proceedings against Trump.