Donald Trump has become the third U.S. president ever to be impeached, but what may be even more notable is that the 73-year-old Republican will be the country's first president to seek re-election after the dramatic rebuke from Congress.

While Trump's job rating has been stable even since the impeachment inquiry began in September, the political fallout of seeking to oust a president as the 2020 election looms -- an issue that has deeply divided the public -- is unclear, experts say.

Trump was impeached by the Democratic-controlled House of Representatives for allegedly abusing the power of his office by pressuring Ukraine to investigate a key political rival in the next presidential election, as well as for obstructing Congress during its impeachment inquiry.

Impeachment is expected to move to the Senate where a trial will be held to decide whether the president should be ousted from office. The Republicans, who dominate the upper chamber, have so far been united in defending Trump, making his removal unlikely.

(President Donald Trump addresses his impeachment during a Merry Christmas Rally at the Kellogg Arena on Dec. 18, 2019 in Battle Creek, Michigan.)
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"The impeachment at this point isn't having any effect (on voters), because it's not moving independents or Republicans against Trump," said Monika McDermott, professor of political science at Fordham University in New York.

In an effort to arouse public opinion on the issue, a House panel held some 30 hours of televised open hearings in November featuring diplomats and other officials, leading to what some U.S. media called "bombshell" testimony highlighting Trump's alleged misconduct.

But public perception of impeachment has not changed much from early October to mid-December, with support for it hovering within a tight band of 48 to 50 percent, the U.S. political journalism company Politico said Wednesday, citing its polls.

"I certainly think that the Democrats hoped that public opinion would be behind them on this (impeachment move), and in that sense, they were wrong, basically," said McDermott, who studies voting behavior, adding that they apparently failed to win new voters over to their side in the process.

A December poll from Politico also showed that views of the impeachment inquiry were split sharply along party lines, with 83 percent of Democratic voters supporting the inquiry and 81 percent of Republicans against it. Among independent voters, 45 percent backed the probe and 41 percent thought otherwise.

On the reason why many voters remained unmovable, the professor suggested that people may have become "immune" to further attacks against Trump amid a flood of negative coverage of the president, who continues to stir controversy with the unconventional leadership style and aggressive rhetoric that have marked his tenure since it began in 2017.

"It just doesn't make any difference to their opinions anymore," she said.

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Failing a strong shift in public opinion toward the need to expel Trump, the Democratic Party may be taking a risky path.

In the previous impeachment case involving Bill Clinton in December 1998, the Republicans seeking to remove the president from office lost House seats in the midterm election earlier that year amid public opposition to the impeachment push.

Clinton, who faced charges of perjury and obstruction of justice over his affair with a White House intern, was later acquitted by the Senate, also controlled by Republicans.

McDermott said the Democrats could similarly pay an electoral price in the latest case for trying to oust a sitting president who in the end will likely be acquitted.

But there are also other factors that could affect the outcome, such as the fact that Clinton maintained a relatively high job approval rating throughout the impeachment proceedings, whereas the figures for Trump have been stable but low -- hovering around the mid-40 percent range, she said.

Other experts warned that Republicans may face risks if they do not keep the envisioned trial short.

John Hudak, a senior fellow in governance studies at the Brookings Institution, said the longer the trial drags on, "something new could come up."

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"The reality of this presidency is that it is wildly unpredictable. I think there are a lot of Republican senators who frankly have no idea what the president said and to whom, and what those actions might actually create within the party. And so the risk of removal still exists, just not with the information and evidence that we currently have," he said.

"And so the longer that this drags out....the more of an opportunity there is for the president to put his foot in his mouth, to go on Twitter, to say something that Republican senators, ultimately, deeply regret."

With 11 months still to go before the presidential election, the political ramifications of the impeachment may also affect Trump's diplomacy.

Japan may become one of the countries Trump can possibly turn to if his election prospects are harmed by impeachment or other factors, given what appears to be an ongoing friendly relationship between Japanese Prime Minister Shinzo Abe and Trump.

But Mieko Nakabayashi, a political science professor at Waseda University in Tokyo, expressed concerns that the Japanese government lacks powerful bargaining tools to use for leverage in case Trump steps up demands on trade and security issues.

"Japan made too many concessions in trade talks with the United States," the professor specializing in U.S. politics said, noting that the deal signed in October has already given Trump much of what he wanted ahead of the election to shore up his support from farmers and manufacturing workers.

The Trump administration has expressed eagerness to start consultations early next year to enter into further negotiations on a broader bilateral trade agreement, while it is also expected to increase pressure on Japan to pay a higher share of the costs of stationing U.S. forces in the country.

"The impeachment is going to be a tough time for Mr. Trump. But it is disappointing that Japan doesn't have strong cards left anymore to use (for future negotiations)," she said.

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