LOUISVILLE, Ky. (CBSDC/AP) — Sen. Rand Paul of Kentucky entered the campaign for the 2016 Republican presidential nomination Tuesday with a declaration that he’s running for the White House to “take our country back.”

“I have a message, a message that is loud and clear and does not mince words — we’ve come to take our country back,” Paul said over chants of “President Paul.”

Paul told supporters he has a vision for America to stop the “Washington machine.”

“The Washington machine that gobbles up our freedoms and invades every nook and cranny of our lives must be stopped,” the Kentucky senator said.

Paul not only took a shot at Democrats over the U.S. debt, but took a swipe at his own party.

“It seems to me that both parties and the entire political system are to blame,” Paul said. “Big government and debt doubled under a Republican administration and is now tripling under Obama’s watch.”

Paul said that Republicans squander their victories by becoming part of the Washington machine.

“Too often when Republicans have won we’ve squandered our victory, becoming part of the Washington machine. That’s not who I am,” Paul told the crowd.

Paul reached out to African-Americans during his speech, stating that “liberal policies have failed our inner cities.”

“Our schools are not equal and our poverty gap continues to widen,” Paul said.

Paul said that he envisions a national defense that is unbeatable and that he will not give aid to foreign countries that hate America.

“Not one penny more for these haters of America,” he said.

The presidential hopeful also said he wants a constitutional amendment to force Congress to balance the budget and he wants to limit the terms of lawmakers.

Paul’s challenge now is to convince Republican primary voters and caucus-goers that his is a vision worthy of the GOP presidential nomination, a prize twice denied his father, former Rep. Ron Paul of Texas.

Hundreds of supporters crowded into a hotel ballroom to hear Rand Paul speak, and many said they had been backers of Ron Paul’s presidential runs.

“Rand, I think, encompasses those same principles (as his father), but he also realizes the pragmatism that is necessary to bring those principles to fruition in American politics today,” said Eric Thomas, a 49-year-old financial services worker from Knoxville, Tennessee, who was waiting for Paul to arrive at his launch event.

Paul begins the 2016 race as just the second fully declared candidate, behind Sen. Ted Cruz of Texas, but he could face as many as 20 rivals for the nomination before the lead-off Iowa caucuses in February.

Along the way, Paul is likely to challenge his fellow Republicans’ views on both foreign and domestic policy, as well as the nuts and bolts of how campaigns are run. Tech savvy and youth-focused, Paul is expected to be an Internet juggernaut that his competitors will be forced to chase.

After his speech in Louisville, Paul was set to answer questions from voters on his Facebook page. Before his announcement speech, he was already selling on his website iPhone cases branded with his logo, signed copies of the Constitution and Rand Paul beer steins.

The online store was a quick way for Paul to collect contact information for voters who want the swag but had not yet considered a direct donation to the candidate.

It’s unclear, though, how much support Paul can muster in the Republican mainstream.

Paul is a frequent contrarian against his party’s orthodoxy, questioning the size of the U.S. military and proposing relaxation of some drug laws that imprison offenders at a high cost to taxpayers. He also challenges the GOP’s support for surveillance programs, drone policies and sanctions on Iran and Cuba.

But as the presidential campaign came closer, Paul has shifted his approach somewhat on the complicated question about how much government the country actually needs.

“The issue on Sen. Paul and national security issues is where he comes down in the continuing conflict between his principles and his ambition,” said John Bolton, a former ambassador to the United Nations and a potential Paul rival for the GOP nomination.

In an interview, Bolton cited Paul’s shifting views on military spending.

In Paul’s proposal for the 2012 budget, he called for reducing military spending and for fewer troops at the Department of Defense. “The DOD should not be treated sacrosanct with regard to the treatment of taxpayer dollars,” Paul wrote in a plan that would balance the federal budget in five years.

But last month Paul proposed a 16 percent increase in the Pentagon’s budget.

“On any given day, it’s hard to know where he will be,” Bolton said. “I believe in redemption, and I hope he comes all the way over. But I just don’t know what’s at work in his mind.”

In another sign of his uphill climb, an outside group not connected to any candidate planned to spend more than $1 million on ads criticizing Paul’s positions on Iran sanctions. The ads were scheduled to start airing asPaul was declaring himself a candidate.

Perhaps reflecting the challenges he faces in convincing his critics he deserves the nomination, Paul is also leaving open the door to a second term in the Senate. With the backing of his state’s senior senator, Majority Leader Mitch McConnell, Paul is likely to seek the White House and the Senate seat at the same time.

McConnell was not expected to attend Paul’s political rally on Tuesday, instead opting for a meeting with the Jessamine County Chamber of Commerce near Lexington.

One of Paul’s likely rivals, Sen. Marco Rubio of Florida, has said he would not double-dip on the ballot. He is expected to announce next week that he will skip a Senate re-election bid in 2016 in favor of putting everything into a presidential campaign.

(TM and © Copyright 2015 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2015 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)