Editor's note:  The article is based on an interview with Xin Qiang, deputy director of the Center for U.S. Studies at Fudan University. It reflects the expert's views, and not necessarily those of CGTN.

As the world is watching the ongoing impeachment farce in the White House, the U.S. State Department has revived its investigation into former secretary of state Hillary Clinton's email scandal. Coincidentally, reports accusing Democrats of colluding with Ukraine in the 2016 presidential election surfaced.

"By ramping up investigation into the email scandal that had been dormant for more than three years, (Donald) Trump is warning Democrats not to go too far on the impeachment inquiry," Xin Qiang, deputy director of the Center for U.S. Studies at Fudan University, told CGTN.

From emailgate to the Clinton Foundation's controversy, which faced accusations of being a pay-to-play scam, to Jeffrey Epstein's alleged connections with high-level officials in the White House, dirty plays have permeated U.S. politics.

But for a long time, pro-establishment GOP figures and Democrats connived to keep all these dirty deals under the table. Despite the rough-and-tumble of bipartisan combat, investigations into the scandals have always ended up with being dropped. Only four presidents, including Donald Trump, have so far been dragged into impeachment danger.

However, as a businessman-turned-president, Trump is known for his anti-establishment stance. This, combined with his unique personality, means that he is unlikely to keep his mouth shut on any dirty Democrat maneuvers, especially when his political career is in jeopardy.

Annoyed at Nancy Pelosi's impeachment inquiry, Trump will apply all possible weapons he can think of – such as reviving the investigation in Clinton's emails – to fight back. The president is sending a clear signal – he would publicize Clinton's alleged dirty plays if Pelosi insists on insulting him regarding his controversial phone call with Ukrainian counterpart Volodymyr Zelensky.

Trump's reigniting the email scandal, according to Xin, may deter Democrats from further aggressive moves. After all, Clinton has been at the core of the Democratic leadership for years. A number of high-level Democrats have inextricable connections with the Clinton family. Investigations on Clinton may eventually drag the entire Democratic Party into the mire.

Moreover, with the clock ticking for the 2020 presidential election, Democrats cannot afford to have their under-the-table deals exposed to the public. The President has enough resources and levers to crack down on the Democratic Party. If the GOP is determined to fight a life-or-death struggle with Democrats, neither would win.

Pelosi had been reluctant to seek to impeach Trump. But the Democratic rank-and-file, especially the ultra-left forces, have become increasingly dissatisfied with the capricious president and voices calling for Trump's impeachment are much louder than before. To boost the morale of the Democrats and unite party members, Pelosi changed her mind.

But if there is no solid evidence to support Trump's collusion with Ukraine, Pelosi's decision may bring more losses than gains, Xin told CGTN, adding that the ongoing inquiry is a double-edged sword to the Democratic Party. If the impeachment attempt fails, Trump's supporters would, for sure, be more united; the swing voters may tilt toward Trump to vent their dissatisfaction against Pelosi's "witch-hunt" and the morale of Democrats would be significantly undermined.

Judging from the current situation, Trump is unlikely to be removed from office. To begin with, no concrete evidence has been provided so far to convict him, even though the White House released the transcript of Trump's controversial phone call last week.

More importantly, even if the Democrat-controlled House voted for the impeachment, the GOP-dominated Senate is highly likely to veto the decision if no concrete evidence is provided.

With a little over a year left before the 2020 presidential election, a full-fledged fight between Republicans and Democrats has now commenced. How the two parties will eventually play in this term's bipartisan farce is left to be seen.

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