(CNN) President Donald Trump is fretting about two rising global challenges that threaten a political gut punch as he gears up for his 2020 election bid -- a possible oil price hike and market shocks triggered by his trade wars.

Both crises will test Trump's capacity to work his will on the world stage as well as the strategic viability of his "America First" foreign policy. A tariff battle with China is highlighting a growing great power rivalry. And Russia's role as a top energy producer with a vested interest in setting global oil prices could open new fronts in a widening confrontation between Washington and Moscow.

The Dow sild 450 points at Thursday's open amid doubts about the US-China truce.

Trade fears are being amplified by the arrest of Meng Wanzhou, the CFO of Huawei and daughter of the Chinese company's founder. China-sensitive stocks such as Apple and Boeing fell 3%.

The President's Twitter account is usually a reliable guide to his frustrations and grievances, and apart from a tribute to George H.W. Bush on the day of his funeral, Trump's feed pulsated with concern Wednesday about market moving events.

He effectively dared ministers of the Organization of Petroleum Exporting Countries (OPEC) meeting in Vienna not to cut production, a move that could reverse a period of lower oil prices and compromise the effectiveness of new US sanctions imposed as part of a new hardline policy on Iran.

"Hopefully OPEC will be keeping oil flows as is, not restricted. The World does not want to see, or need, higher oil prices!" Trump wrote.

But most analysts expect OPEC to cut production by up to 1.5 million barrels a day to reverse a glut partly triggered by a previous US request to pump more oil as a cushion against the impact of the new sanctions on Iran.

Such a move could not only spark further volatility of global markets, it could push up the cost of gas in the United States, ending a period of lower pump prices welcomed especially by lower income workers in rural areas key to Trump's political base.

An OPEC production cut could also cast doubt on the effectiveness of one of Trump's most controversial foreign policy moves -- holding Saudi Arabia close despite the suspected role of the kingdom's Crown Prince Mohammed bin Salman, known as MBS, in the murder of Washington Post columnist Jamal Khashoggi in Turkey.

Trump is under extreme pressure in Congress for standing by MBS and support is building among lawmakers for a ban on arms sales and new sanctions against the kingdom. Trump, however, partly justified his refusal to cut the Saudis loose by noting their importance in global oil markets.

"Oil prices getting lower. Great! Like a big Tax Cut for America and the World. Enjoy! $54, was just $82. Thank you to Saudi Arabia, but let's go lower!" Trump tweeted on November 21.

Standing by the Saudis

Trump last month explained his solidarity with the Saudis in the plainest expression yet of a foreign policy approach rooted in the idea that traditional US concerns about human rights should be superseded by a drive to maximize commercial advantage from the nation's foreign relationships.

"We're not going to give up hundreds of millions of dollars in orders and let Russia and China have them ... it's a very simple equation for me. I'm about make America great again," the President said.

But Trump's domestic exposure on Saudi Arabia is only getting worse.

Senate Republicans are now in open and rare revolt against the Trump White House, raising the possibility that a veto-proof majority may exist to override any attempt by the President to exert control over Saudi policy.

Top Trump ally South Carolina Republican Sen. Lindsey Graham accused the Saudis of being a "wrecking ball" that is jeopardizing US security interests in the region.

Trump critics who believe the President's Saudi policy is also being influenced by his own business interests will seize on a Washington Post report Wednesday that lobbyists representing the kingdom paid for an estimated 500 nights in his Washington DC hotel over three months shortly after he was elected.

Democrats plan to probe any financial links between Trump and the Saudis when they take control of the House of Representatives in January.

MBS might feel beholden to US requests to limit oil production cuts, given the President's public and constant support at a time when the Saudi prince is being ostracized across the world. But though it is hugely influential, Saudi Arabia cannot control what OPEC does.

The oil-producing Canadian province of Alberta for instance has announced it will cut production to reverse over supply that has lowered Canadian crude prices.

Another important influence in OPEC is Russia, which is not a member of the organization but has shown signs it is willing to join in a cut in production.

Given the importance of high oil prices to Russia's economy and increasing geopolitical strains with the US, exacerbated by Trump's decision to cancel a meeting with President Vladimir Putin in Argentina over the weekend, Moscow may be in no mood to throw the US a political bone.

Trump also anxious about China duel

The oil price puzzle and the temporary halt to a tariff war that Trump negotiated with China's President Xi Jinping during the weekend G20 summit exemplify the gamble Trump often takes with his unorthodox global leadership.

A deepening trade war with China and rising oil prices, in defiance of US demands, could have knock-on effects that could weaken Trump's political support, his argument that Americans are better off under his leadership and damage strong economic growth -- his best argument for a second term.

China's reprisals to billions of dollars in tariffs imposed on its exports have, by design, disproportionately targeted areas on which Trump is counting for support in 2020, including agricultural states like Iowa that he won in 2016.

So while lambasting China on the campaign trail and accusing the Asian giant of stealing US industrial jobs made for a strong message in the Midwest, the measures Trump used to make good on his promises have had a political cost.

Trump's Twitter feed again betrays his current obsessions -- he has tweeted about his trade deal with Xi seven times in just the last 36 hours. His effort was part of a damage control bid by the President and other senior officials to bolster an agreement with the Chinese that seems in retrospect to be even less comprehensive than it initially appeared.

"Very strong signals being sent by China once they returned home from their long trip, including stops, from Argentina," Trump tweeted on Tuesday.

"Not to sound naive or anything, but I believe President Xi meant every word of what he said at our long and hopefully historic meeting. ALL subjects discussed!"

Very strong signals being sent by China once they returned home from their long trip, including stops, from Argentina. Not to sound naive or anything, but I believe President Xi meant every word of what he said at our long and hopefully historic meeting. ALL subjects discussed! — Donald J. Trump (@realDonaldTrump) December 5, 2018

The Dow Jones Industrial Average slumped nearly 800 points on its most recent day of trading Tuesday as investors realized that the agreement between Trump and Xi may not stave off hostilities for long.

"This tariff situation still looms large over the market," JJ Kinahan, chief market strategist at TD Ameritrade, told CNN on Tuesday.

On Wednesday, however, China moved to ease some of those concerns after its initial reticence to offer details of what it had signed up to rattled the markets and angered Trump.

Beijing belatedly recognized a 90-day clock for talks and reaffirmed its willingness to implement "already-agreed-on specific points as quickly as possible" a move that Trump noted when he tweeted about "very strong signals."

The White House also says the deal with Xi will see China buy large amounts of US agricultural produce to close the trade deficit and includes an agreement by Beijing to curtail the flow of fentanyl, a powerful opioid, into the US.

In return, Trump agreed to hold off on plans to raise all current tariffs to 25% on January 1.

After frequently boasting about a bull run during most of the first two years of his presidency, Trump has shown recent signs of concern about the optics of plunging stock markets that have now given up most of the year's gains.

The Wall Street Journal reported last month that Trump had soured on Treasury Secretary Steven Mnuchin partly owing to stock market volatility, his support for Federal Reserve Chairman Jerome Powell and a more conciliatory approach to China than some hawkish White House advisers.

Trump denied the report, but it added to the impression that the President is increasingly concerned about how the economic turbulence abroad could weaken his political viability at home.