Following sweeping midterm election victories that gave Republicans full control of Congress, Sen.-Elect Cory Gardner, R-Colorado, said that the GOP now has to prove it can "govern maturely" and with competence if it hopes to fix a broken Washington and hold onto gains made in 2014.

"You have to fix it right out of the box, I believe, by working together, Republicans and Democrats, putting ideas forward on the president's desk, ideas that the broad majority of American people support, and showing that we can govern," Gardner told "This Week" anchor George Stephanopoulos Sunday.

"I think it's important that Republicans show that we can govern maturely, that we can govern with competence," Gardner added. "And if we do that, in two years from now, we'll have a good result again with our nominee. If we don't, we'll see the same results two years from now, but in a different direction."

Gardner struck a conciliatory tone on "This Week," saying that shutting down the government "is a bad idea anytime, anywhere" and that although he supports repealing and replacing the Affordable Care Act, it was not a feasible option while President Obama still occupies the White House.

"I do think we need to repeal and replace Obamacare, but the president named Obama is not going to repeal a bill named Obamacare," Gardner said.

And Gardner said he hopes President Obama will "do the right thing" and work with Congress on immigration reform rather than taking executive action on his own before the end of the year.

"The question is this: Will the president do the right thing? And I think the president will do the right thing when it comes to immigration reform. And that is working with the House and the Senate instead of going around the House and the Senate," Gardner said.

Gardner offered advice to the 2016 GOP nominee for president if they intend to win a state captured by President Obama in 2008 and 2012, saying it requires an "optimistic message."

"More than anything, in this Rocky Mountain state, people want to be able to lift their eyes up to the great Rocky Mountain horizon and recognize the fact that we have an ever-hopeful state, and that's the kind of message that we had to capture to make sure that people were proud again and to make sure that we can build toward a government that we can be proud of," Gardner said.

Like "This Week" on Facebook here. You can also follow the show on Twitter here. Go here to find out when "This Week" is on in your area.