Trump attorney Bruce Castor opened by praising the "outstanding presentation" from House impeachment managers, noting what Rep. Jamie Raskin, D-Md., and his family endured "during that terrible day."

"You will not hear any member of the team representing former President Trump say anything but in the strongest possible way denounce the violence of the rioters and those that breached the Capitol, the very citadel of our democracy, literally the symbol that flashes on television whenever you're trying to explain that we're talking about the United States, instant symbol," Castor said.

Notably, Castor referred to Trump as "the former president," a term the Trump team has avoided using in their press releases.

Castor, a former Montgomery County, Pennsylvania, district attorney faced criticism in that role for declining to prosecute Bill Cosby in 2005.

The Senate returned from a 10-minute break following the arguments from the House impeachment managers.

Trump's legal team has taken the floor with Bruce Castor opening with his argument that it's unconstitutional to put a former president on trial.

House impeachment manager Rep. Jim Cicilline, D-R.I., offered an early rebuttal to arguments expected from Trump's legal team, beginning by arguing that the former president is not merely a private citizen, saying that he "he can and should answer" for his use of power.

Cicilline also read a tweet from Trump that was posted hours after the attack and once again falsely claiming the election was "stripped" from him. Cicilline said that tweet "chills him to the core."

"The president of the United States sided with the insurrectionists, he celebrated their cause, he validated their attack, Cicilline said. "He told them, 'remember this day forever,' hours after they marched through these halls looking to assassinate Vice President Pence, the speaker of the house and any of us they could find."

Cicilline also pushed back on the expected argument that the impeachment is partisan and could enflame partisan tensions.

"They'll assert that this impeachment is partisan and that the spirit of bipartisanship and bipartisan cooperation requires us to drop the case and march forward in unity. With all due respect, every premise and every argument of that conclusion is wrong. Just weeks ago, the president of the United States literally incited an armed attack on the capitol, our seat of government, while seeking to retain power by subverting an election he lost and then celebrated the attack," Cicilline said. "People died, people were brutally injured. President Trump's actions endangered every single member of Congress."

-ABC News' Benjamin Siegel

Rep. Jamie Raskin, D-Md., the lead House impeachment manager, bookended the Democrats opening' arguments on the constitutionality of the trial by recalling how the day impacted him personally, and, fighting back tears, directly called on his colleagues to "not let this be our future."

"Senators, Mr. President, to close I want to say something personal about the stakes of this decision whether President Trump can stand trial and be held to account for inciting insurrection against us," Raskin said. "I hope this trial reminds America how personal democracy is and how personal is the loss of democracy too."

He explained that his youngest daughter, Tabitha, was with him at the Capitol on Wednesday, Jan. 6. because it was the day after they buried her brother, his son, Tommy, "the saddest day of our lives," Raskin said.

"Also there was my son-in-law Hank, who's married to our oldest daughter Hannah, and I -- I consider him a son too, even though he eloped with my daughter and didn't tell us what they were going to do," Raskin joked, and got a laugh, before pivoting into his emotion-filled recollection of the rest of the day.

"The reason they came with me that Wednesday, Jan. 6, was because they wanted to be together with me in the middle of a devastating week for our family," he said. "They said they heard that President Trump was calling on his followers to come to Washington to protest and they asked me directly, 'Would it be safe? Would it be safe?' I told them, 'Of course it should be safe. This is the Capitol.'"

Raskin was separated from them for electoral business when rioters breached the building.

"And all around me people were calling their wives and their husbands, their loved ones to say goodbye. Members of Congress in the House were removing their congressional pins so they wouldn't be identified by the mob as they tried to escape the violence. Our new chaplain got up and said a prayer for us, and we were told to put our gas masks on," he said.

Raskin said the sound he'll never forget, the "most haunting sound I've ever heard" is one of "pounding on the door like a battering ram."

He said his staff, hiding, "thought they were going to die," and when he finally reunited when his daughter and son-in-law, a comment she made hit him, perhaps, hardest.

"I told her how sorry I was, and I promised her it would not be like this again the next time she came back to the Capitol with me. You know what she said? She said, 'Dad, I don't want to come back to the Capitol,'" Raskin said, fighting back tears. "Of all of the terrible, brutal things that I saw and that I heard on that day, and since then, that one hit me the hardest."

"That and watching someone use an American flag with the flag still on it, to spear and pummel one of our police officers ruthlessly, mercilessly tortured by a pole with flag on it that he was defending with his very life," he added, emphasizing the deaths and injuries from that day.

"We cannot have presidents inciting and mobilizing mob violence against our government and our institutions because they refuse to accept the will of the people under the Constitution of the United States. Much less can we create a new January exception in our precious, beloved constitution that prior generations have died for and fought for, so that corrupt presidents have several weeks to get away with whatever it is they want to do," he said to close his time.

After the Senate decided it will not call any witnesses, lead House manager Rep. Jamie Raskin, D-Md., was the first to speak during closing arguments. He reiterated the prosecution's case, calling for the conviction of Trump.

"It was suggested by defense counsel that Donald Trump's conduct during the attack, as described in Congresswoman Beutler's statement, is somehow not part of the Constitutional offense for which former President Trump has been charged," Raskin began. "I want to reject that falsehood and that fallacy immediately. After he knew that violence was underway at the Capitol, President Trump took actions that further incited the insurgents to be more inflamed and to take even more extreme, selective, and focused action against Vice President Mike Pence."

Raskin went on to use his time to describe Trump's months-long campaign to discredit the 2020 election results by spreading misinformation, which he argued laid the groundwork for deadly events of Jan. 6. He went on to claim that the former president assembled the mob, incited it and then sent it off to the Capitol during his speech. At every point, Trump sided with the insurrectionists rather than the Congress, Raskin said.

Once when the violence began, Raskin declared that Trump ignored the violence and further incited it by aiming the attacks on his own vice president.

"There has never been a greater betrayal by the president of the United States of his office, and of his oath to the Constitution."

Raskin then took a moment to suggest the GOP used "cancel culture" against one of its leaders, Rep. Liz Cheney, R-Wyo., who voted to impeach Trump in the House.

"Liz Cheney is a hero for standing up for the truth, and resisting this retaliatory cancel culture that she was subjected to."

Raskin emphasized his gratitude toward the Capitol Police, and finished his argument by saying convicting Trump is a vote for the "security of our democracy."

"They attacked this building, they disrupted the peaceful transfer of power, they injured and killed people, convinced that they were acting on his instructions, and with his approval, and protection," Raskin finished. "And while that happened, he further incited them, while failing to defend us. If that's not ground for conviction, if that's not a high crime and misdemeanor against the republic in the United States of America then nothing is. President Trump must be convicted for the safety and security of our democracy and our people."