There are now four grounds to impeach Donald Trump and a fifth is "on its way", according to former Labour Secretary Robert Reich.
Posting on Twitter, Mr Reich outlined the four reasons he thinks Mr Trump could be impeached.
He said Mr Trump is "'unfaithfully' executing his duties" by accusing former President Barack Obama of "undertaking an illegal (and impeachable) act."
Last weekend, Mr Trump accused Mr Obama of wiretapping his phones in Trump Tower, though he provided no evidence for his claim.
A spokesman for Mr Obama denied he ever ordered the wiretapping of any US citizen.
Mr Reich also said although part of the constitution forbids government officials from taking things of value from foreign governments, "Trump is making big money off his Trump International Hotel by steering foreign diplomatic delegations to it, and will make a bundle off China's recent decision to grant his trademark applications for the Trump brand — decisions Chinese authorities arrived at directly because of decisions Trump has made as president."
China recently granted preliminary approval for dozens of Trump-branded businesses, including new hotels, spas, massage parlours and personal security services.
The former Labor Secretary also said Mr Trump's ban on travel from six Muslim-majority countries violates the 1st Amendment of the Constitution, which bans any law "respecting an establishment of religion or prohibiting the free exercise thereof."
He also said Mr Trump "labelling the press the 'enemy of the people' and choosing whom he invites to news conferences based on whether they've given him favourable coverage" could be another reason for impeachment, as he said it violates the 1st Amendment on the freedom of the press.
Finally, he wrote: "Article III Section 3 of the Constitution defines 'treason against the United States' as 'adhering to their enemies, giving them aid and comfort.' Evidence is mounting that Trump colluded with Russian operatives to win the 2016 presidential election."
Mr Trump has repeatedly denied his team had contact with Russian officials during the 2016 election, but was revealed to have met with Russia's US ambassador at the height of his campaign.
The controversial orders Donald Trump has already issued
The controversial orders Donald Trump has already issued
1/9 Trump and the media
White House Press Secretary Sean Spicer takes questions during the daily press briefing
2/9 Trump and the Trans-Pacific Partnership
Union leaders applaud US President Donald Trump for signing an executive order withdrawing the US from the Trans-Pacific Partnership negotiations during a meeting in the Roosevelt Room of the White House in Washington DC. Mr Trump issued a presidential memorandum in January announcing that the US would withdraw from the trade deal
3/9 Trump and the Mexico wall
A US Border Patrol vehicle sits waiting for illegal immigrants at a fence opening near the US-Mexico border near McAllen, Texas. The number of incoming immigrants has surged ahead of the upcoming Presidential inauguration of Donald Trump, who has pledged to build a wall along the US-Mexico border. A signature campaign promise, Mr Trump outlined his intention to build a border wall on the US-Mexico border days after taking office
4/9 Trump and abortion
US President Donald Trump signs an executive order as Chief of Staff Reince Priebus looks on in the Oval Office of the White House. Mr Trump reinstated a ban on American financial aide being granted to non-governmental organizations that provide abortion counseling, provide abortion referrals, or advocate for abortion access outside of the United States
5/9 Trump and the Dakota Access pipeline
Opponents of the Keystone XL and Dakota Access pipelines hold a rally as they protest US President Donald Trump's executive orders advancing their construction, at Columbus Circle in New York. US President Donald Trump signed executive orders reviving the construction of two controversial oil pipelines, but said the projects would be subject to renegotiation
6/9 Trump and 'Obamacare'
Nancy Pelosi who is the minority leader of the House of Representatives speaks beside House Democrats at an event to protect the Affordable Care Act in Los Angeles, California. US President Donald Trump's effort to make good on his campaign promise to repeal and replace the healthcare law failed when Republicans failed to get enough votes. Mr Trump has promised to revisit the matter
7/9 Donald Trump and 'sanctuary cities'
US President Donald Trump signed an executive order in January threatening to pull funding for so-called "sanctuary cities" if they do not comply with federal immigration law
8/9 Trump and the travel ban
US President Donald Trump has attempted twice to restrict travel into the United States from several predominantly Muslim countries. The first attempt, in February, was met with swift opposition from protesters who flocked to airports around the country. That travel ban was later blocked by the Ninth Circuit Court of Appeals. The second ban was blocked by a federal judge a day before it was scheduled to be implemented in mid-March
SANDY HUFFAKER/AFP/Getty Images
9/9 Trump and climate change
US President Donald Trump sought to dismantle several of his predecessor's actions on climate change in March. His order instructed the Environmental Protection Agency to reevaluate the Clean Power Plan, which would cap power plant emissions
"The question is no longer whether there are grounds to impeach Trump. The practical question is whether there is the political will," Mr Reich concluded.
"As long as Republicans remain in the majority in the House (where a bill of Impeachment originates), it's unlikely.
"Another reason why it's critically important to flip the House in 2018."Reuse content