President-elect Donald Trump gave himself a pat on the back today via Twitter, as several companies announced new investments in the U.S. and, in turn, more American jobs.

'With all of the jobs I am bringing back into the U.S. (even before taking office), with all of the new auto plants coming back into our country and with the massive cost reductions I have negotiated on military purchases and more, I believe the people are seeing "big stuff," he wrote using two tweets.

In a third tweet, which came after lunch, Trump wrote: 'Thank you to General Motors and Walmart for starting the big jobs push back into the U.S.!'

On the jobs front this morning, General Motors announced a plan to invest an additional $1 billion into the American economy, while Walmart said it will create 10,000 new retail jobs.

Hyundai also said today it would increase its U.S. investment by 50 percent.

German drug giant Bayer AG announced plans to buy up the American company Monsanto, but with that, also invest in 3,000 new jobs.

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President-elect Donald Trump suggested he had been successful in bringing back a lot of jobs to the U.S. - 'even before taking office' - as he'll be sworn in on Friday

President-elect Donald Trump said he believed the people are seeing 'big stuff' as new jobs were announced today - though also new, low poll numbers for the president-elect

The new Bayer-owned Monsanto would also keep retain the 9,000 jobs already in the United States.

Incoming Press Secretary Sean Spicer told reporters of the news today on a conference call following the president-elect's meeting with top executives of both companies last week.

Hyundai's announcement – that the company will raise its investment to $3.1 billion over five years and may build a U.S. plant – comes in response to Trump's threat to tax automobile imports, Reuters pointed out.

Walmart, the retail giant, announced the retail positions in advance of Trump's inauguration, as the president-elect has promoted an 'America First' agenda.

The company plans to build new stores and renovate old ones, which it says will add 24,000 construction jobs as well.

General Motors' new investment accounts for 1,500 new or retained U.S. jobs.

The company also said it would be insourcing axle production for its newest pickup truck line and that move would create another 450 American jobs.

Some of those jobs, General Motors pointed out in the announcement, had previously been in Mexico.

After lunch, Donald Trump got more specific and applauded General Motors and Walmart for announcing new U.S. jobs

Trump had criticized the company on Twitter on January 3 saying, 'General Motors is sending Mexican made model of Chevy Cruze to U.S. car dealers-tax free across border.'

Politifact rated that statement mostly true, as NAFTA provisions in this example allowed the imported cars from Mexico to come across the border tax free, though in Mexico only hatchback Cruzes are made, accounting for just 15 percent of the sales of the vehicle globally.

The Ohio-made sedan is 40 times more popular with American buyers.

Since being elected, Trump has Twitter-shamed Toyota, for planning to build Corollas in Mexico, and also Lockheed Martin and Boeing, for charging the government too much for planes, including a new Air Force One.

He's touted the plans of Ford and Fiat Chrysler, as the companies have committed to making U.S. investments.

In early December, Trump gave the nation a taste of how he would run things, by making a trip to Indiana to tout a deal with Carrier that would keep some U.S. jobs at home.

That move, according to a Politico/Morning Consult poll, gave Trump high marks, with 60 percent of respondents saying they viewed the president-elect more favorably.

Trump's boasts today, however, came on the heels of new, low approval ratings.

CNN put out a survey today that said that Trump would take office with numbers more than 20 points lower than those of his three predecessors.

President Barack Obama had an approval rating of 84 percent when he took office in 2009, President George W. Bush stood at 61 percent in 2001 and President Bill Clinton stood at 67 percent in 1993.

Trump has an approval rating of 40 percent.

Getting on Twitter this morning, he spoke of the 'record numbers' coming into D.C. for his inauguration and called the CNN poll 'phony' and 'rigged' before making the jobs boast.

He also reengaged with Rep. John Lewis, D-Ga., the civil rights leader who is boycotting Trump's inauguration over the Russians' interference in the election.

Trump said Lewis was wrong – or lied – when he claimed that this was the first inauguration he had skipped, as the Democratic congressman also didn't attend the first inauguration of Bush 43, who, like Trump, lost the popular vote to the Democratic nominee.