A last-minute reversal by Republican Senator Rand Paul overnight has seen CIA Director Mike Pompeo avoid a historic rebuke by the US Senate Foreign Relations Committee — where a nominee for secretary of state has never received a negative recommendation.

Mr Pompeo's confirmation as America's top diplomat now looks even more certain when the full Senate decides on his nomination in the coming days.

If he does get confirmed, Mr Pompeo will inherit a State Department that has seen calls for drastic cuts to its budget, a mass exodus of career diplomats, vacancies in virtually all of its senior positions and widespread reports of plunging morale.

He will also take office at a time when multiple events are coming to a head: the fate of the Iranian nuclear deal, a possible presidential summit with North Korea's Kim Jong-un and a potential trade war with China.

Mr Pompeo's appointment would have several significant implications for US foreign policy.

Pompeo's confirmation as Secretary of State would further embolden the more hawkish elements within the administration, but also could potentially temper some of the president's more impulsive actions.

As his secret trip to North Korea demonstrated, Mr Trump clearly trusts him. Because of his relationship with the president, Mr Pompeo stands a good chance of elevating the role of diplomacy and significantly boosting morale at the State Department.

And due to their public alignment on key policy issues and Mr Trump's apparent trust, his confirmation as Secretary of State would further embolden the more hawkish elements within the administration, but also could potentially temper some of the president's more impulsive actions.

'On the same wavelength' as Trump

Prior to his appointment by Mr Trump to lead the CIA, Pompeo served as a three-term congressman from Wichita, Kansas, where he came to power on the wave of Tea Party Republicans.

He became known for his aggressive partisanship while serving on the House Select Committee on Benghazi, Libya that, after more than two years of investigations, found no evidence of wrongdoing by then secretary of state Hillary Clinton.

At the CIA, Mr Pompeo cultivated a close personal relationship with the President. He attended Mr Trump's daily intelligence briefing and, according to press accounts, was often asked to accompany the President to his next meeting or weigh in on various domestic and foreign policy matters.

Opining on policy is a departure from the normal role of the CIA director, though it was apparently his views, his demeanour, and his support that earned him Mr Trump's trust.

"Tremendous energy, tremendous intellect," Mr Trump said of Mr Pompeo. "We are always on the same wavelength."

Pompeo's tougher line on Russia

Mr Pompeo's public statements on Iran, China, North Korea, climate change, and counterterrorism are in line with the President's.

But on other issues, most notably on Russia, Mr Pompeo has taken a stronger line.

Pompeo has pledged to counter Russian assaults on western democracy, advocated for a more meaningful punishment of Moscow's advances in Ukraine and in Syria, and after some prevarication called out Russian interference in America's 2016 presidential election.

He has pledged to counter Russian assaults on western democracy, advocated for a more meaningful punishment of Moscow's advances in Ukraine and in Syria, and after some prevarication called out Russian interference in America's 2016 presidential election.

On all of this he has been careful not to get too far out in front of the President, but because of Mr Trump's fondness for him, he has been able to carve out a separate position without yet having Mr Trump publicly undercut him. This matters greatly for the role he is likely to step into.

Tillerson couldn't speak for Trump

During his year-long tenure, Rex Tillerson was unable to speak credibly on behalf of the President or cultivate even the appearance of a close relationship.

He failed to exercise influence on the administration's polices on key issues, and was unable to get the White House to sign off on his preferred appointments.

State Department employees consistently complained about his management style, which ignored and demoralised the department's public servants, and his unwillingness to fight for State's budget.

He proved unwilling to defend the President's more outrageous positions and his seeming disdain for the diplomatic press corps earned him consistently bad media coverage.

Many Washington insiders have already concluded that Mr Tillerson will go down as one of the worst modern Secretaries of State.

An easier road for Pompeo

Here, Mr Pompeo has an easy and obvious path ahead of him.

As a political insider, he has worked hard at cultivating good relations with Congress, other Cabinet officials, foreign leaders and the press.

Moreover, his demonstrated ability to ingratiate himself to Mr Trump and his full-throated advocacy for the President's positions are likely to make him a much more forceful and credible defender of the administration's foreign policy.

Having worked closely with Pompeo over the last year, the Australian Government has welcomed news of his appointment, with Prime Minister Malcolm Turnbull saying that for Australia the transition would be "absolutely seamless".

Given these factors, if confirmed, Mr Pompeo can boost morale within the State Department, expand its influence and serve Mr Trump as a trusted advisor.

To do so, he'll have to push the White House to fill the many vacant diplomatic posts at State and US embassies around the world and reverse the decision to drastically cut diplomatic and development funding.

He will have to balance earning favourable press coverage without seeming to upstage Mr Trump.

Perhaps most critically, Mr Pompeo will also have to determine the optimal balance between spending time with the President and traveling abroad to reassure allies, fleshing out hitherto nebulous messages such as the "free and open Indo-Pacific" and laying the diplomatic groundwork for key policy decisions ranging North Korea to Iran to Syria.

Good news for beleaguered State Department

If confirmed, and as long as Mr Trump does not publicly undercut him, Mr Pompeo's appointment will correctly be seen — both in Washington and abroad — as elevating the importance of the State Department.

Publicly, he's likely to bring State and the White House into closer coordination and he may be able to articulate a more coherent view of American foreign policy abroad.

Privately, if he chooses to do so, he may have the potential to temper some of Mr Trump's impulses. Mr Tillerson was seen as a responsible, if ineffective, policy advocate. Mr Pompeo's views are much more synced with the President and therefore could result in a greatly enhanced role for the State Department and diplomacy in this administration.

Having worked closely with Mr Pompeo over the last year, the Australian Government has welcomed news of his appointment, with Prime Minister Malcolm Turnbull saying that for Australia the transition would be "absolutely seamless".

As Secretary of State, he would begin his tenure both empowered to speak on behalf of Mr Trump and better able to convey key messages to the President from allies.

Of course, Mr Trump's trust has proven a waning asset for most members of his Cabinet.

It is unclear how long Mr Pompeo would remain in favour — particularly if he took a stance that either contradicted or was seen to undercut Mr Trump.

Thus far, however, Mr Pompeo has shown himself able to walk that fine line.

With Mr Pompeo at the helm, Australia should expect a more empowered and effective State Department and a more assertive and coordinated policy in Washington.