PALM BEACH, Florida — President Trump’s lawyers will argue that House Democrats have launched a “dangerous attack” on the right of the people of the United States to choose their own leader when his impeachment trial resumes on Tuesday, according to sources close to his legal team.

Their strategy is laid out in a six-page response to a summons sent by the Senate that is expected to be filed on Saturday evening — the team's first formal response to the charges. It sets out the White House argument that Democrats have failed to show the president broke the law.

According to the sources, the text states: “The articles of impeachment submitted by House Democrats are a dangerous attack on the right of the American people to freely choose their president. This is a brazen and unlawful attempt to overturn the results of the 2016 election and interfere with the 2020 election now just months away.”

The source said the response would tackle both procedural and substantive concerns with the two articles of impeachment, alleging that Trump abused his position and obstructed Congress.

“We next assert that the articles of impeachment are constitutionally invalid on their face,” he said. “They fail to allege any crime or violation of law whatsoever, let alone high crimes and misdemeanors.”

Trump became the third president to be impeached when the House last month approved charges that he abused his power by asking the president of Ukraine to open a corruption investigation into former Vice President Joe Biden’s son. He is accused of withholding aid in order to increase pressure.

However, the document spells out that security assistance was sent to Ukraine without an investigation being launched.

It also states that the president has a legitimate right to withhold information through executive privilege, which cannot therefore constitute obstruction of Congress.

Impeachment moves into its next critical phase this week. Trump’s Senate trial is expected to start on Tuesday, and his lawyers are due to submit their “legal brief,” setting out a more detailed argument, on Monday.

“The conclusion at the end of the day is that the articles violate the Constitution,” said a source. “They are defective in their entirety. They are the product of invalid proceedings that flagrantly denied the president and due process rights. They rest on dangerous distortions of the Constitution that will do lasting damage to our structure of government.”

The briefing came just before House Democrats were due to outline their case for removing Trump in a legal brief on Saturday evening.

A day earlier, the White House announced that several nationally known lawyers would be joining Trump’s legal team, including Ken Starr, the prosecutor whose investigation led to the impeachment of President Bill Clinton, and former Harvard law professor Alan Dershowitz.