Trump could face GOP challengers in the 2020 election Some Republican lawmakers have made moves that may be signs of 2020 runs.

 -- As President Trump’s approval among Republican voters drops, speculation looms about potential challengers from the GOP before the 2020 election.

Just over six months into his presidency, a CNN poll released Tuesday found that Trump’s strong approval rating among Republicans has fallen to 59 percent, down from 73 percent in February. According to the poll, only 35 percent of whites without college degrees, a key component of Trump’s base, strongly approve of Trump — down 12 percentage points since February.

The New York Times reported Saturday that Republicans, including donors and elected officeholders, expressed uncertainty to the Times about Trump’s place in the next presidential race.

The administration has been quick to denounce such claims. Counselor to the president Kellyanne Conway told ABC News’ chief anchor George Stephanopoulos during a Sunday appearance on “This Week” that Trump “plans on being a two-term president.”

Nonetheless, some Republicans are making moves that could be interpreted as signs of a 2020 run — from trips to Iowa to meetings with donors.

Vice President Mike Pence

Perhaps the most controversial of all suspected 2020 presidential contenders is Vice President Mike Pence. After a New York Times article on Saturday pointed out signals of Pence’s possible presidential ambitions and reported that “multiple advisers to Mr. Pence have already intimated to party donors that he would plan to run if Mr. Trump did not,” Pence pushed back forcefully.

“Today’s article in The New York Times is disgraceful and offensive to me, my family and our entire team. The allegations in this article are categorically false and represent just the latest attempt by the media to divide this administration,” he said in a statement released Sunday morning.

The Times argued that Pence’s packed vice presidential schedule, nods to party donors, the recent hire of political operative Nick Ayers as his chief of staff and appearances at high profile events, including Iowa Sen. Joni Ernst’s pig roast, were notable signs that Pence may have big plans for 2020. His creation of a PAC, the Great American Committee, has been interpreted by some as a sign he may challenge Trump. Neither Vice President Joe Biden nor Vice President Dick Cheney created PACs until they left office. Pence’s press secretary Marc Lotter told Fox on Monday that the PAC was created only out of “legal necessity.”

Marty Obst, a Pence aide, also denied to The New York Times that he and Ayers made any private insinuations to donors that Pence wants to be ready for 2020.

Gov. John Kasich

Ohio Gov. John Kasich, who ran for the GOP presidential nomination in 2016, has not ruled out entering the 2020 race. He was the last candidate to withdraw from the 2016 race, after efforts to present himself as a more traditional Republican than Trump. Kasich joined efforts with fellow candidate Sen. Ted Cruz of Texas in attempts to reduce Trump’s delegate count during the primaries.

In an interview with CNN in April, Kasich said it is “very unlikely” that he would enter the race but added, “How do you close the door on anything? ... If I see something I need to do to help my country that I really believe that I have to do, then I would think I would probably do it.”

He has spoken out recently against the GOP’s health care repeal efforts and plans to convene a series of forums on health policy. As part of a book tour, he has traveled across the country, including to New Hampshire, where he placed second in its 2016 primary. He may not serve another term after his second term ends in January 2019.

UN Ambassador Nikki Haley

Nikki Haley, the former South Carolina governor who was appointed by Trump to serve as the U.S. ambassador to the United Nations, has also been mentioned as a possible challenger to Trump in 2020. She criticized him during the 2016 campaign and supported Marco Rubio but has come to be a powerful player in Trump’s administration.

Tuesday morning on “Fox & Friends,” Haley appeared to suggest that Trump tweeted about classified information. Asked about a story appearing on FoxNews.com regarding North Korean activity to load anti-ship cruise missiles in a patrol boat, she responded, “I can't talk about anything that’s classified. And if that’s in the newspaper, that's a shame.” Trump had retweeted the Fox News story that morning.

Haley responded to questions on whether the administration will embrace a report on climate change drafted by scientists at 13 federal agencies, which The New York Times first reported on Monday night. “I haven't seen the report. But I don’t see any reason why they wouldn’t. A lot of this is, we’re not saying that climate change is not real. It is real,” she said. Trump has been a longtime critic of government spending and regulations on climate change and pulled out of the Paris Climate Accord in June. Haley also said, “Just because we pull out of the Paris Accord doesn't mean we don’t believe in climate protection.”

Steve Schmidt, a GOP strategist who managed Sen. John McCain’s 2008 presidential campaign, told Politico that Haley is “one of the few political leaders ... who’s had consistently good moments on the political stage over the past few years.” In spite of talk about her political rise, she told CNN in April she couldn’t “imagine running for the White House.”

Sen. Tom Cotton

Arkansas Sen. Tom Cotton has risen as a prominent national conservative. Though Cotton raised speculation of a 2020 bid, he has recently been working alongside Trump. Cotton partnered with the president and Georgia Sen. David Perdue to push an immigration bill, which has no co-sponsors, that focuses on merit and skills over family affiliation in determining who is permitted to immigrate to the United States. In a May interview with Politico’s “Off Message” podcast, Cotton said, “Donald Trump won, and he’s the president, and everybody needs to accept that, especially the Democrats.” However, he also said, “That doesn’t mean I’ll support every policy he announced or every statement he makes.”

The Associated Press reported that he took a trip to Council Bluffs, Iowa, in May, where he delivered a speech at the Pottawattamie County Republican Party’s annual fundraiser. The speech, which was directed at an audience of over 100 Iowa GOP supporters and received a standing ovation, had seemingly presidential tones, with Cotton calling for “that new beginning.”

He will be hosting a $5,000 per person fundraiser in September, signaling large fundraising efforts. However, as AP reported, when he was asked whether he was building a framework for a 2020 presidential bid, he replied, “No.”

Sen. Jeff Flake

Jeff Flake, the junior senator from Arizona, has been a top critic of the president in the GOP. Flake would not endorse Trump during the 2016 campaign and recently released a book titled “Conscience of a Conservative: A Rejection of Destructive Politics and a Return to Principle,” which largely centers on his disapproval of Trump.

In return, the Trump administration has met with several potential challengers to Flake, who is up for re-election in 2018. Flake has not announced any plans to run in 2020 but continues to position himself as a Trump critic.

Sen. Ben Sasse

While only a first term senator, Ben Sasse has gained recognition in part because of his criticism of Trump. Sasse, who represents Nebraska, refused to support Trump during the campaign and in an open letter on Facebook wrote that if Trump became the nominee, he would support a “third candidate — a conservative option, a constitutionalist.”

Sasse’s new book, “The Vanishing American Adult,” does not explicitly mention Trump but focuses on the failure of current American culture and political virtue. Sasse visited Iowa earlier this year, claiming the trip was a result of a lost bet. He did not directly respond when asked on CNN in July if there was any chance he would challenge Trump.

How likely is it there will be a different GOP nominee in 2020?

Trump has given no sign that he will not run for re-election in 2020.

Of the Republicans seen as possible challengers, some may simply be gearing up early for 2024 and beyond. Nonetheless, the amount of speculation about a GOP challenger to Trump in 2020 suggests a lack of unity in the party and behind the president.