Johnny Isakson may have just delivered the most important speech of his U.S. Senate career.

In a four-minute address to Senate colleagues, Isakson – up for re-election in 2016 – declared that he preferred to cast his vote to defund Obamacare, even if he loses, rather delay that vote and participate in the GOP effort to shut down the federal government.

If you haven't followed this closely, you might be confused by today's situation in the Senate.  Senate Majority Leader Harry Reid is attempting to bring a House-passed bill -- that would a) extend government funding until December, but b) would remove funding from Obamacare -- to a vote in the Senate as quickly as possible. To give House-Senate negotiators as much time as possible to avoid a Monday midnight shutdown of the federal government.

Democrats would also strip the "defund Obamacare" portion of the legislation in the process.

The "defund-or-bust" crowd in the Senate -- Ted Cruz of Texas, Mike Lee of Utah, and Marco Rubio of Florida -- want to delay the vote until Saturday, presumably in order to ratchet up pressure on Reid and the White House to accept the conditions that House Republicans want to tack on. Delayed Senate action, already postponed by Cruz' filibuster, increases the chances of government disruption next week.

His is a delicate line, but Isakson says it's time for the game-playing to end, and for the GOP to accept the current mathematics of Congress. Otherwise, Republicans risk a voter backlash like the one that stung the GOP after the shutdown of 1995/96, he warned. “It cost us a speakership. It cost us leadership in the House, and politically, that’s unsustainable and something we shouldn’t do,” he said.

You can watch the video above, or read the rough transcript below:

“Madam President, I rise to discuss the current dilemma before the Senate, with regard to whether or not to vote for the motion to close debate and go to… the final vote, if you will, on the House-passed version of the CR, which strips – which puts in the language which defunds Obamacare.

“I will vote ‘yes’ for cloture, so we can go to the vote that I have promised my constituents in my state. Fifty-seven different times, in other votes, I’ve cast in the Senate -- in favor of defunding Obamacare because I believe there is a better way to do it.

“We only have two options before us. One is to end debate and go to a vote on legislation passed out of the House, that will continue the government, and defund Obamacare – understanding the [Democratic] leadership will have an amendment to strip the defunding out. Which I will vote against that amendment, because I want to be consistent with the other 57 votes that I have taken.

“But the other alternative is … not to shut off debate, to continue the debate, which means we come up to Monday night, midnight, when the fiscal year ends and the government shuts down. Government shutdowns are a bad idea. They are bad for the people to send us…to represent them, they’re bad for seniors on Social Security, they’re bad those whose husbands and sons and daughters who are fighting in harm’s way in Afghanistan and other parts of the world.

“It hurts our military, it hurts our health care system, and it doesn’t do anything to stop Obamacare. What a lot of people don’t realize is, [if] you shut the government down – you’re not shutting down Obamacare. A great percentage of that is mandatory funding. If you shut the government down, you’re actually encouraging Obamacare, and discouraging our government to function as it should.

“I will not vote to shut the government down. I will vote to end the debate, and I will vote in the way that I’ve promised every citizen in my state since the Obamacare legislation came before us.

“Look, I’m on the [Senate] Health Committee. We did the mark-up on the Affordable Care Act in 2009. Like all almost every other member of the United States Senate, I was here on Christmas Eve 2009 and voted against the Obamacare legislation on the final vote. Since that period of time, we’ve had a plethora of votes and challenges and opportunities – and I have remained consistent.

“I’m not going to, all of a sudden, at a debate, change my consistency and vote to shut down the government and continue Obamacare. I want to be consistent with the way I voted. I want the Senate to take up its responsibilities. I want to be sure we do not shut down the government for our people, I want to be sure everybody in the Senate has their opportunity to cast their vote – both on the continuing resolution, and whether Obamacare stays, or whether Obamacare is defunded.

“That is the question before us. Not whether or not we shut the government down. So while I respect and appreciate everybody’s position, I just think it’s irresponsible for us as a Senate to knowingly and voluntarily shut down our government, extend Obamacare -- when we have the opportunity to have the debate, have the vote, strip out the funding for Obamacare, and move forward….

“I don’t know how it will end up. I think I know. But I know one thing: Inaction and not voting is wrong. People of Georgia sent me here to take action, not to avoid action. They sent me here to run the government, not to shut the government down.

“In fact, I got to the United States Senate, and the United States House, because of a government shutdown, and I want to tell that story. In the 1990s, when President Clinton was president and Newt Gingrich was [House] speaker, many issues came about on fiscal spending and the speaker and the president and the majority leader of the Senate, Bob Dole, got in a conflict over extending the budget.

“The Republicans took the position – we’ll shut the government down rather than yield to what President Clinton wanted to do. So the government was shut down. About three weeks later, the government was brought back. Speaker Gingrich came back and capitulated. We reopened the government, but we lost a lot of ground. Two years later, he was re-elected by a narrow margin, but was not re-elected speaker and resigned.

“I replaced him. Careful -- if you shut the government down, you might get another me. So that’s what happened. The voters speak out. The voters make sure that we’re accountable and responsible. It cost us a speakership. It cost us leadership in the House, and politically, that’s unsustainable and something we shouldn’t do.

“I want to be a part of doing my responsible action, voting like I told my voters I’m going to vote, instead of shutting the government down, having the vote to see which way we’re going to move forward as a country…. “