Sen. Mark Warner (D-Va.) is "encouraged" by the principles a group of senators unveiled Monday for passing immigration reform.

Warner sent the tweet about an hour after Sens. Charles Schumer (D-N.Y.), Dick Durbin (D-Ill.), John McCain (R-Ariz.), Bob Menendez (D-N.J.), and Marco Rubio (R-Fla.) unveiled a slate of immigration reform principles. Sens. Michael Bennet (D-Colo.), Jeff Flake (R-Ariz.), and Lindsey Graham (R-S.C.), who also helped craft the outline, were not at the press conference.

Both Democrats and Republicans in Congress have signaled openness to passing immigration reform in 2013. Earlier on Monday, White House press secretary Jay Carney said President Obama "welcomes the efforts" by the eight senators.

"This is a big deal. This is an important development," Carney said at the White House daily briefing. 

Obama is set to deliver a speech on immigration reform Tuesday in Las Vegas.