Former Pennsylvania Senator Rick Santorum launched his bid for the Republican Party's presidential nomination for the 2012 election, defending his principles despite a losing his seat in 2006, backing a Republican plan to change Medicare for future seniors to let them purchase private health insurance.

Americans are looking for someone who has stood by his principles in good times and in bad, the social and fiscal conservative told Good Morning America on Monday ahead of the official announcement.

Santorum said he didn't back off of trying to reform the social security system in 2006, the year he lost a Senate election.

I did some things that were very unpopular, but if you look at what I did and when I did it people can say, you know what? He may have lost but he didn't flinch. He stood by what he believed in and he continued the fight through the end.

Santorum also stood by a Republican plan that would that would reform Medicare and which would take effect a decade from now that would subsidize seniors' purchases of private healthcare plans. Seniors over age 55 would not have their plans changed from the current version of Medicare.

Almost 25 percent of seniors right now have what the Ryan plan is. It's called Medicare Advantage. And in fact that number was growing up until Barack Obama slashed the program, he said.

GMA host George Stephanopoulos interjected, saying, But that's an option.

Well, the point is seniors were able to take the money and go out and purchase insurance. And by the way the seniors who were most likely to do it were lower income and actually less educated seniors, why? Because they found it was a better deal, he said.

Santorum also says the United States, under President Barack Obama, have been appeasing foreign countries such as Iran, who are moving ahead with their nuclear program.

They know that the President is not going to do anything to stop them, he is a paper tiger and they are the existential threat to the state of Israel. The Israelis know it and the Americans know it. This President has not stepped forward. He has not done anything to stop that threat.

Look at what he's doing in Syria, slapping the hand of Assad instead of going after him at least as tough as he went after our friend Mubarak, he said.