Sen. Bernie Sanders, I-Vermont, says he'll be able to build a giant grassroots movement of support to win the Democratic nomination and the 2016 election, but that he'll also go one step further than President Obama did successfully harness his grassroots support to change Washington.

In an interview on CBS' "Face the Nation" Sunday, Sanders said that the president ran "one of the great campaigns in the history of the United States of America" in 2008, but he also made a mistake by trying to negotiate fair compromises with Republicans and their leadership in Congress.

"The truth is Republicans never wanted to negotiate, all they wanted to do is obstruct," Sanders said. "What I have said throughout this campaign is electing Bernie Sanders as president is not enough. Not going to do it. We need a mass grassroots movement that looks the Republicans in the eye and says, 'If you don't vote to demand that your wealthy people start paying their fair share of taxes, if you don't vote for jobs, raising the minimum wage and expanding Social Security, we know what's going on, we're involved, we're organized, you are outta here if you don't do the right thing.'"

He plans to build that grassroots coalition by bringing more people into the political process and focusing heavily on poverty and income inequality.

"I'm going to be going around the country not only to blue states...but to red states, conservative states. We're going to go to Alabama, we're going to go to Mississippi," Sanders said. "I think the message that we have is resonating. People are going to get involved in the political process, we're going to drive turnout up and when we do that we win."

Sanders has been attracting thousands of people to his campaign events and gaining in the polls against Hillary Clinton, his chief rival for the Democratic nomination. He still resists personal attacks against Clinton, but is quick to draw differences in their positions. Sanders cites his commitment to breaking up large financial institutions on Wall Street, his vote against the Iraq War, and opposition to the Trans-Pacific Partnership trade deal.

In a separate interview on "Face the Nation," House Speaker John Boehner predicted that Sanders will give Clinton "a real run for her money" in the Democratic primary but said that both candidates are "out of step with mainstream America" because "there's no limit to the number of taxes that Bernie Sanders and Hillary Clinton want to raise."

Sanders responded by going after Boehner for refusing to bring up legislation to raise the minimum wage, which has broad support among the American people. He also said the Republican Party defies Americans' wishes by looking to privatize or cut Social Security benefits and being reluctant to spend any money to rebuild infrastructure.

"In terms, John, of who's out of touch with the American people I would say the Republican Party is," Sanders told host John Dickerson. "They want to give tax breaks to billionaires not help the middle class."

In the interview, Sanders also declared himself "a great fan of Pope Francis" for his vocal criticism of income inequality in the U.S.

"I think Pope Francis has played an extraordinary, extraordinary role. He has been a voice of conscience all over the world speaking out for those people who don't have a voice, those people who are suffering, and what he's saying is enough is enough," Sanders said. "Money cannot be the god of life...We have got to come together to create a new world and not a world in which a handful of people have so much wealth and so many other people are suffering."

Francis will address a joint session of Congress on Sept. 24 during his visit to the United States.