By Patricia Zengerle and Steve Holland
WASHINGTON/PALM BEACH, Fla. (Reuters) - The Democratic U.S. lawmakers leading the impeachment case against Republican President Donald Trump said on Saturday the president must be removed from office to protect national security and preserve the country’s system of government.
In a brief filed ahead of a 5 p.m. EST (2200 GMT) deadline, the lawmakers laid out their arguments supporting charges of abuse of power and obstruction of Congress against the president.
"The Senate should convict and remove President Trump to avoid serious and long term damage to our democratic values and the nation's security," the lawmakers said, for the first time formally calling for the Senate to convict the president and remove him from office.
“The case against the president of the United States is simple, the facts are indisputable, and the evidence is overwhelming," they said.
Trump issued a resounding rejection of the House of Representatives' impeachment, calling the charges against Trump an attempt to overturn the 2016 election.
"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," Trump's legal team argued in a six-page document released on Saturday.
It was the first time Trump had formally addressed the merits of the two articles of impeachment - abuse of power and obstruction of Congress - that the Democratic-led House approved late last year.
The two articles, aimed at ousting Trump from office, form the basis of a trial that will begin in earnest on Tuesday in the Republican-controlled Senate.
"We are on strong legal footing. The president has done nothing wrong and we believe that will be borne out in this process," said one of three sources close to the Trump legal team who briefed reporters on a conference call about the contents of the document.
Trump, at his Mar-a-Lago club in Palm Beach, Florida, for the weekend, played a round of golf on Saturday.
The Trump impeachment response will say the case against the president is "nothing more than a dangerous attack on the American people" and their right to vote, the sources said.
The document will argue that the articles of impeachment violate the U.S. Constitution and would do lasting damage, they said.
Trump is accused of abuse of office for pressuring Ukraine to investigate a political rival, former Vice President Joe Biden, and of obstructing Congress in its investigation into his conduct.
“An acquittal would also provide license to President Trump and his successors to use taxpayer dollars for personal political ends,” the Democratic lawmakers' brief said.
Trump has denied wrongdoing and has accused Democrats of a partisan-driven effort to undo his 2016 election victory.
The Senate trial is unlikely to lead to Trump's ouster, as no Republican senators have voiced support for doing so.
The Trump lawyers, in their document, argued that Trump acted at all times with full constitutional legal authority, the sources said.
"We will take the facts head on and we believe that the facts will prove, and have proven, that the president did absolutely nothing wrong," said one of the sources.
