Sen. Mark UdallMark Emery UdallSenate GOP rejects Trump’s call to go big on gun legislation Democratic primary could upend bid for Colorado seat Picking 2018 candidates pits McConnell vs. GOP groups MORE (D-Colo.) proposed that the Speaker of the House as well as the majority and minority leaders of both houses of Congress sit together during President Obama's State of the Union speech later this month, in a letter dated Wednesday.

Udall, the senior senator from Colorado, writes in the letter — addressed to Speaker John BoehnerJohn Andrew BoehnerFreedom Caucus bruised but unbowed in GOP primary fights GOP revolts multiply against retiring Ryan Can Jim Jordan become top House Republican? MORE (R-Ohio), Senate Minority Leader Mitch McConnellAddison (Mitch) Mitchell McConnellTeacher defeats Kentucky state House majority leader in GOP primary Conservatives leery of FBI deal on informant Lobbying world MORE (R-Ky.), Senate Majority Leader Harry ReidHarry Mason ReidMcConnell not yet ready to change rules for Trump nominees The Hill's Morning Report — Sponsored by CVS Health — Trump’s love-hate relationship with the Senate Trump to press GOP on changing Senate rules MORE (D-Nev.) and House Minority Leader Nancy Pelosi (D-Calif.) — that political rhetoric has become especially "corrosive" lately and that sitting together during Obama's speech would symbolize an end to heightened political hostilities between Democrats and Republicans.

"This departure from statesmanship and collegiality is fueled, in part, by contentious campaigns and divisive rhetoric," Udall writes. "Political differences will always generate a healthy debate, but over time the dialogue has become more hateful and at times violent."

So Udall's proposal is to completely end the tradition of sitting with fellow party members during the presidential address, including minority and majority leaders.

"At the State of the Union address, on January 25th, instead of sitting in our usual partisan divide, let us agree to have Democrats and Republicans sitting side by side throughout the chamber," Udall continues in the letter. "Beyond custom, there is no rule or reason that this night should emphasize divided government, separated by party, instead of being seen united as a country. The choreographed standing and clapping of one side of the room — while the other side sits — is unbecoming of a serious institution."

Political rhetoric and symbolism has become a major topic among Republicans and Democrats in the days since the Arizona shooting on Saturday that resulted in six dead and 14 injured, including Rep. Gabrielle Giffords (D-Ariz.). Both conservatives and liberals have blamed the opposite group's inflamed rhetoric for creating an environment that may in part have led to the shooting.

"On the night of the state of the Union address, we are asking others to join us — House and Senate members from both parties — to cross the aisle and sit together," writes Udall.