President Donald Trump said Monday that a trade agreement had been reached with Mexico in an Oval Office announcement.

He called it a 'big day for trade' and a 'big day for our country' in remarks.

Trump said the North American Free Trade Agreement was a 'rip-off' for the U.S. and the new pact, which he called United States-Mexico Trade Agreement, will be 'incredible' for both countries.

The president said he was getting rid of the name NAFTA because it has a 'bad connotation' and the United States was hurt for many years by the trilateral deal between the U.S., Canada and Mexico. He claimed he was 'terminating' the previously established deal altogether.

His celebration, which featured a live telephone call with the Mexican president, may have been premature.

Canada had not signed onto the agreement as of Monday afternoon, although direct talks were due to continue, and the U.S. hoped the neighbor with which it shares its northern border would join in the new accord before the White House issues a mandatory notice to Congress. Officials said they hoped to be able to submit the necessary documentation by Friday.

President Donald Trump said Monday that a trade deal had been reached with Mexico in an Oval Office announcement

A senior U.S. official admitted on a call with reporters, however, that the Trump administration couldn't be certain that Mexico would move forward with an accord if Canada does not sign on.

The official said that for more 'clarity' on the matter reporters should 'maybe ask the Mexicans' while proclaiming that without support from Canada 'we'll move on bilaterally.'

Trump's top economic adviser also waved off journalists noting that the pact hadn't been signed yet. He told reporters as he was reentering the White House after a CNBC interview that it need only be formally drawn up.

A legal dispute was also raging on Monday over the United States' ability to replace the trilateral agreement with one that excluded Canada.

President Trump said in his Oval Office announcement he would give Canada a chance to 'probably have a separate deal' although they could also join the new pact.

'One way or another we’ll have a deal with Canada. It’ll either be a tariff on cars or it’ll be a negotiated deal,' he said. 'Frankly, a tariff on cars is a much easier way to go.'

It was not immediately clear what the newly-agreed upon deal actually said. Trump hinted that it included a security component, saying that Mexico is 'going to be helping us at the border,' but officials were unable to say Monday what the pact might say about illegal immigration.

A fact sheet provided by the U.S. trade representative's office did not mention the dispute over illegal immigrants flooding the United States' southern border by way of Mexico as part of what was said, either.

It mainly highlighted agreements in the agricultural sector such as labeling requirements for cheese, wine and spirits.

A letter to Congress notifying lawmakers of the deal was to be submitted on Friday. In 90 days, after a mandatory waiting period, Trump said he'd sign the new deal into law.

Trump said that he would be 'terminating' the existing, three-party accord that he's hammered for years once the new one is in place.

He also said he'd be speaking with Canadian Prime Minister Justin Trudeau 'in a little while' to discuss next steps.

Jared Kushner, a senior adviser to the president as well as his son-in-law, lauded the agreement as a 'win-win transaction' that will hopefully pave the way for a 'lot more to come'

ALL THE WAY UP: The Dow was up 259 points on Monday at closing bell

On a call with reporters, U.S. officials shared the broad contours of a deal, explaining that it would cover a period of 16 years. A formal review will take place every six years, with a provision to move to annual reviews if either party determines the deal needs reworking.

A U.S. official described it as 'a rolling forward of the agreement timeframe with real opportunity for review that will keep both modernizing on track and keep disputes from festering.'

'Ideally, Canada will be in, and we'll be able to notify that,' the senior official said. 'If Canada is not in, then we'll notify that we have an agreement with Mexico and that we're open to Canada joining it.'

Jared Kushner, a senior adviser to the president as well as his son-in-law, lauded the agreement as a 'win-win transaction' that will hopefully pave the way for a 'lot more to come.'

'The president obviously is fighting for America. He’s fighting for our workers, he’s fighting for our companies. And he’ll be tough but end of the day he’ll be fair and we present this deal ultimately with his leadership that he thought was a fair deal that would make our country better,' Kushner said. 'And so he was happy to do it.'

Trump's long-awaited trade announcement, which the White House added to his schedule suddenly on Monday, was in disarray from the moment he appeared on camera, however. Not only was a formal accord still being hammered out, how exactly the deal would be married with existing U.S. trade law had not been laid out.

In a horrifying moment, Trump struggled to get Mexican President Enrique Pena Nieto on the phone to congratulate him on achieving a deal.

'Hello?' the U.S. president said repeatedly on camera, before the outgoing leader, whose term ends at the beginning of December, joined the line. 'It's a big thing. A lot of people waiting. Hello?' Trump again said.

Speaking in Spanish, Pena Nieto said he wants Canada to join the agreement and congratulated Trump on having the 'political will' to push an accord through

Speaking in Spanish, Pena Nieto said he wants Canada to join the agreement and congratulated Trump on having the 'political will' to push an accord through.

But Pena Nieto referred to the status as a 'point of understanding' between the two nations in an English translation.

'I wish -- that the part with Canada will be materializing in a very concrete fashion; that we can have an agreement the way we proposed it from the initiation of this renegotiating process, a tripartite,' he said in the White House's transcript. 'And I hope that in the following days we can materialize [on the understanding ] in the formalization of the agreement.'

Pena Nieto suggested that they have a 'good toast with tequila' - forgetting, perhaps, that the American president doesn't drink - and told him he sends an 'affectionate hug.'

Trump called him a 'friend' in response and said they got 'know each other quite well' when, as a candidate, he went to see Pena Nieto in Mexico.

The U.S. president said they 'had a good meeting,' despite subsequent claims of a rift between the two leaders, and teased at the end of the call that a 'hug from you would be very nice.'

On the call with reporters, a U.S. official claimed there's also no 'tension' between Trump and Trudeau.

'I don't know that there is any tension,' the senior administration official said. 'Leaders of nations tend to do what's in the interest of their nation.'

Trudeau and Trump have been at odds since the U.S. slapped countries, including Canada, with heavy steel and aluminum tariffs. The trade disagreement turned into a full-scale argument after a fight following this year's G7 summit

Trudeau and Trump have been at odds since the U.S. slapped countries, including Canada, with heavy steel and aluminum tariffs. The trade disagreement turned into a full-scale argument after a fight following this year's G7 summit.

Trump was enraged by a slap that Trudeau took at him after he'd departed. He sent his senior economic adviser, Larry Kudlow, on television to accuse the Canadian PM of 'betrayal' and has having 'stabbed us in the back.'

'We were very close to making a deal with Canada on NAFTA, bilaterally perhaps, and then we leave and Trudeau pulls this sophomoric, political stunt for domestic consumption,' Kudlow told CNN.

Since then, Washington had been suggesting that it could go it alone in a deal with Mexico and come back to Canada later. And on Monday, Trump was poised to do exactly that.

'Canada will start negotiations shortly. I'll be calling the Prime Minister very soon. And we'll start negotiation, and if they'd like to negotiate fairly, we'll do that,' he said. 'You know, they have tariffs of almost 300 percent on some of our dairy products, and we can't have that. We're not going to stand for that.'

Trump, who has said all along that he'd prefer two bilateral deals with Mexico and Canada over the trilateral deal that's currently in place, indicated on Monday over Pena Nieto's pushing that he wants to move forward on a deal with or without Trudeau.

'We can have a separate deal or we can put it into this deal. I like to call this deal the United States-Mexico Trade Agreement. I think it's an elegant name. I think NAFTA has a lot of bad connotations for the United States because it was a rip-off,' he said. 'It was a deal that was a horrible deal for our country, and I think it's got a lot of bad connotations to a lot of people.'

Trump said that he and Pena Nieto would put their heads together to come up with a new trade agreement name.

'We will see whether or not we decide to put up Canada or just do a separate deal with Canada, if they want to make the deal. The simplest deal is more or less already made. It would be very easy to do and execute,' he said.

Kudlow told reporters later that negotiations with Canada would 'restart' as a result of the agreement with Mexico and described the talk between Trump and Trudeau that took place in the afternoon as 'a good conversation.'

Canadian officials were due to arrive in Washington on Tuesday, Kudlow said.

'I hope they watch carefully, how these things can get done.'

The president hinted that a trade deal was imminent in a tweet on Saturday morning

The president said he was getting rid of the name NAFTA because it has a 'bad connotation' and the United States was hurt for many years by the trilateral deal between the U.S., Canada and Mexico in his morning announcement

Trump had hinted that a first draft of a pact was on the brink of emerging on Monday, saying in a morning tweet, 'A big deal looking good with Mexico!'

The White House said shortly after that Trump would be making an 11 am statement on the topic of trade.

The United States and Mexico were said to have reached partial agreement, with President Trump announcing Saturday that a 'big' deal could be going down soon.

'Our relationship with Mexico is getting closer by the hour,' he said. 'Some really good people within both the new and old government, and all working closely together....A big Trade Agreement with Mexico could be happening soon!'

Parties to the North American Free Trade Agreement have been negotiating for months to re-do the Clinton-era trade document.

Earlier this year, the president imposed tariffs on steel and aluminum, which angered allies and raised pressure for a new deal, as talks continued with Canada.

The Dow Jones Industrial average jumped 200 points on Monday in advance of Trump's announcement that negotiators had finally struck a deal with Mexico, and closed 259 points above where it had been at opening bell.

'Today is Mexico Day,' Kudlow announced on CNBC. 'The market loved it.'

He told reporters on the White House driveway after the interview that the 'expectation' is that Mexico will move forward with a bilateral agreement, even if Canada doesn't sign on.

'The indications are, we're going to sign this document with them, the end of the week, and they're fine with, it's going to go forward.'

A firm agreement remained elusive as Monday came to a close.

Kudlow admitted, 'It's an agreement in principle.' But insisted, 'That's pretty good.'

The apparent agreement included a provision requiring a greater share of auto manufacturing be done in high-wage factories – meant to insulate U.S. firms from cheaper Mexican labor, the Washington Post reported.

Pressure was on negotiators to finish a deal before Mexico's new president, Andrés Manuel López Obrador, is sworn in December 1.

Hello, hello are you there? Trump had difficulty getting Mexican President Enrique Pena Nieto on the line on Monday for their joint announcement

'Today is Mexico Day,' White House economic council head Kudlow announced on CNBC. 'The market loved it'

The Dow Jones Industrial average jumped 200 points on Monday in advance of Trump's announcement; the S&P was also up

House Majority Leader Kevin McCarthy, who is close to Trump, said Sunday that the expectation is that Canada will be in a hustle to move, too.

'I believe we're very close. And also, remember, we make policy in the world of politics. Remember what politics were going on. Mexico was having a presidential election. So it's very hard for them to make an agreement at the time,' he told 'Sunday Morning Futures' on Fox News.

'That election is over, but the new president is not sworn in. First thing this administration did was go down there,' he said. 'It only makes us stronger, and you're going into a new election next year in Canada, it's beneficial to them to have this all agreed upon this year.'

Lopez Obrador issued optimistic statements about Trump following his election in Mexico, indicating the potential for a thaw between the two nations, after angry clashes over immigration issues.

Speaking fondly of the new Mexican president on Monday, Trump told Pena Nieto he he was 'impressed' at how the two presidents 'came together for your country.'

'So it's an incredible deal. It's an incredible deal for both parties. Most importantly, it's an incredible deal for the workers and for the citizens of both countries. Our farmers are going to be so happy,' the U.S. president said.

Trump campaigned on ripping-up NAFTA, and even as talks progressed, his administration clashed with both of its North American neighbors.

Negotiators appeared to lock down two provisions in recent days.

One related to the percentage of a car that that must be made in North America to receive duty-free treatment. This would jump to 75 percent from the current 62.5 percent. Another would set a percentage of vehicles that must be manufactured in high-wage factories.