Obama on shutdown: ‘Not going to pay a ransom for America to pay its bills’

President Barack Obama held a rare press conference Tuesday, fielding questions on the government shutdown and debt ceiling deadline.

"We're not going to pay a ransom for America to pay its bills," Obama insisted, calling on Congress to "stop the excuses," hold a vote and end the shutdown.

"My message to the world is the United States has always paid its bills and will do so again," Obama said, attempting to reassure global markets and creditors who have expressed concern over the looming debt ceiling, also knon as the borrowing limit.

"Nobody in the past has seriously threatened to breach the debt ceiling until the last two years," he said, adding that he was happy to talk with Republicans, once they reopened government and raised the debt ceiling.

"I've shown myself willing to go more than halfway in these conversations," Obama said. He indicated he would be willing to accept a short-term extension of the debt ceiling while negotiations were taking place.

He warned that the current state of domestic politics is hurting the United States' credibility around the world and threatens the global economy. "Warren Buffett likened default to a nuclear bomb, a weapon too horrible to use."

Treasury Secretary Jack Lew has already employed "extraordinary measures" to keep paying the government's bills, Obama said. He added that though the government is "exploring all contingencies" in case of default, "no option is good in that scenario."

Lew will address Congress on Thursday.

Obama once again excoriated Congress for manufacturing crises, saying, "And to all the American people, I apologize that you have to go through this stuff every three months, it seems like."

House Speaker John Boehner made a short statement following Obama's speech, in which he cited historical examples of presidents negotiating over the debt ceiling.

He said that Obama's position that "we're not going to talk to you until you surrender" was not the United States' system of government.

"The long and short of it is, there's going to be a negotiation here," Boehner said.

Obama spoke to Boehner Tuesday morning, urging him to hold a vote on a budget bill that would reopen the government, and "allow a timely up-or-down vote in the House to raise the debt limit with no ideological strings attached," according to the White House.

Boehner said he was willing to negotiate over the budget and the debt ceiling without preconditions, saying on Tuesday, "I'm not drawing any lines in the sand," according to the Associated Press.

However, Obama has indicated that he will not negotiate over the government shutdown or the debt ceiling.

Boehner, speaking to reporters after a meeting with House Republicans, said that Obama and Senate Majority Leader Harry Reid were "putting our country on a pretty dangerous path" by "refusing to negotiate," The Washington Post reported.

"Listen, there’s never been a president in our history that did not negotiate over the debt limit," Boehner said, but he did not specify what his demands would be in negotiations.

The White House released a statement saying Obama was "willing to negotiate with Republicans — after the threat of government shutdown and default have been removed — over policies that Republicans think would strengthen the country."

Reid's response on Tuesday was: "Open the government, raise the debt ceiling and we’ll talk about anything you want to talk about."

Meanwhile, the International Monetary Fund and the United States' top creditors, Japan and China, have warned that a US default would prove devastating.

"The effects of any failure to repay the debt would be felt right away, leading to potentially major disruptions in financial markets, both in the United States and abroad," said Olivier Blanchard, the IMF's chief economist.

Only nine days remain until the United States hits its borrowing limit, the debt ceiling.