In a letter to House Speaker Nancy Pelosi, Vice President Mike Pence said he would not invoke the 25th Amendment and remove the president.

"I am grateful for the leadership that you and other congressional leaders provided in reconvening Congress to complete the people's business on the very same day. It was a moment that demonstrated to the American people the unity that is still possible in Congress when it is needed most," he wrote. "But now, with just eight days left in the President's term, you and the Democratic Caucus are demanding that the Cabinet and I invoke the 25th Amendment. I do not believe that such a course of action is in the best interest of our Nation or consistent with our Constitution."

He continued, "Last week I did not yield to pressure to exert power beyond my constitutional authority to determine the outcome of the election, and I will not now yield to efforts in the House of Representatives to play political games at a time so serious in the life of our Nation."

In conclusion, he urged Pelosi and members of Congress to avoid actions that would further divide and inflame the passions of the moment.

"Work with us to lower the temperature and unite our country as we prepare to inaugurate President-elect Joe Biden as the next President of the United States. I pledge to you that I will continue to do my part to work in good faith with the incoming administration to ensure an orderly transition of power. So help me God," he wrote.

The House of Representatives is debating a resolution urging Vice President Mike Pence to invoke the 25th Amendment and remove Trump from office over his role in last week's attack on the Capitol.

With Democrats holding a majority in the chamber, the measure is expected to pass. However, Pence given no public indication that he plans to take action.

Democrats are expected, then, to move forward with impeaching Trump on one article -- charging him with "inciting an insurrection." At least 218 Democrats and three House Republicans have indicated their support to impeach the president.

-ABC News' Mariam Khan

The House Judiciary Committee has released a 76-page staff report laying out Democrats' case for impeaching Trump over his role in the violent attack on the U.S. Capitol last week.

"President Trump has falsely asserted he won the 2020 presidential election and repeatedly sought to overturn the results of the election. As his efforts failed again and again, President Trump continued a parallel course of conduct that foreseeably resulted in the imminent lawless actions of his supporters, who attacked the Capitol and the Congress. This course of conduct, viewed within the context of his past actions and other attempts to subvert the presidential election, demonstrate that President Trump remains a clear and present danger to the Constitution and our democracy," an excerpt from the report reads.

"The House must reject this outrageous attempt to overturn the election and this incitement of violence by a sitting president against his own government. President Trump committed a high Crime and Misdemeanor against the Nation by inciting an insurrection at the Capitol in an attempt to overturn the results of the 2020 Presidential Election," it concludes.

The House is expected to vote to impeach Trump as early as Wednesday -- making him the first president in history to be impeached twice.

-ABC News' Katherine Faulders

Senate Majority Leader Mitch McConnell has privately acknowledged he believes Trump committed impeachable offenses and that he is pleased Democrats are moving to impeach him, believing it will make it easier for the Republican Party to be rid of Trump, a source confirmed to ABC News.

The New York Times first reported the development.

McConnell has not said publicly whether he'd vote to impeach Trump and a McConnell spokesman declined to comment.

At least three House Republicans -- Rep. Liz Cheney, Wyo., Rep. John Katko, R-N.Y. and Rep. Adam Kinzinger, R-Ill. -- have said they will vote to impeach the president.

-ABC News' Trish Turner

The Delaware Humane Association hosted a virtual party with over 10,000 people to celebrate the first shelter dog moving into the White House.

While Champ and Major won't put their paws in the White House until Wednesday, the association held the fundraiser Sunday to celebrate the history being made: Major was adopted by Biden in March 2018.

"It means everything to us because it shines a light on the work we do," Delaware Humane Association's executive director Patrick Carroll said Sunday during the virtual party. "It shows that shelters are a wonderful place to adopt."

The shelter showed off photos of Major during his stay there in 2018 along with video of him and the president-elect. It also revealed dog "secretaries" which were dogs from its shelter that were selected by fans.

The Delaware Humane Association raised over $100,000, according to its host.

Biden's two German shepherds will also be the first dogs to live in the White House in four years, though Champ is no stranger to Washington. The Biden family brought the dog into their home in 2008 and he resided with them during his two terms as vice president.