Besieged Deputy President Rigathi is facing a historic moment as the 67-member Senate begins hearing his proposed motion for removal from office by impeachment.
The Senate has scheduled a two-day marathon to hear and ultimately determine Gachagua's fate after the National Assembly passed his impeachment motion last week.
With the sword of Damocles hanging over his head as he heads to the Senate, Gachagua could be living on borrowed time as the country's second in command.
His anticipated removal from office has triggered intense lobbying within the corridors of power with sources aware of the intrigues saying Gachagua's replacement could be named before Mashujaa Day on October 20.
However, the National Assembly would have to conduct approval hearings for Gachagua's successor before the next deputy president is sworn in.
The former one-term Mathira MP who rose from a powerful District Officer in the Moi era to become the country's second in command, is sitting on the cusp of history.
If the Senate confirms his impeachment on Thursday, Gachagua would become the first-ever second in command to be successfully removed from office by Parliament.
Insiders say Gachagua is heavily banking on the divisions in the ruling Kenya Kwanza alliance and the cracks that have permeated the Azimio coalition to rescue his political career at the Senate.
Gachagua needs at least 23 senators to survive his ouster.
He would be deemed to have been removed from office if at least 45 of the 67 senators voted to uphold any of the 11 charges against him.
The DP is expected to take to the stand at the Senate on Thursday to counter the charges against him.
Gachagua will present evidence, and affidavits at 1 pm on Thursday.
The DP's lawyers have remained tight-lipped on the lawyers on the names of the witnesses they will call on Thursday.
Currently, there are fears that while President William Ruto commands numbers in the Senate, recent intrigues regarding the succession's replacement have caused some ripples.
Some of the Mount Kenya politicians who unanimously voted to send Gachagua packing in the National Assembly are said to have reportedly changed their minds amid fears that the succession race has taken different dimensions.
It was initially believed that Interior Cabinet Secretary Kithure Kindiki would be the automatic replacement but lobbying has seen more names floated, causing disaffection in Mount Kenya.
For instance, MPs from Mount Kenya East, where Kindiki comes from, voted overwhelmingly for the impeachment because of the belief that the CS would replace Gachagua.
Imenti Central MP Moses Kirima exposed the fault lines in Kenya Kwanza saying MPs from his region voted to impeach Gachagua because they had been promised the Kindiki would succeed the DP.
"When we were asked to support the impeachment motion only Prof Kindiki was mentioned as the next deputy president. After Gachagua was impeached every community is now lobbying for the DP seat,'' he said.
An impeachment would confine Gachagua out of public service for life as he would be considered unfit to hold such office in line with the leadership and integrity law.
The looming condemnation by the Senate is seen as the reason why Gachagua has put up a multi-pronged strategy to block his ouster including filing multiple cases in court.
However, he suffered two consecutive setbacks on Tuesday and Wednesday after the course failed to block the Senate from proceeding with Gachagua's trial until the cases filed are determined.
Justices Eric Ogolla, Anthony Mrima and Freda Mugambi ruled that at this stage, they can only exercise restraint and allow independent institutions of government to function unhindered.
They cited separation of powers saying courts should be reluctant to take over mandates of other arms of government.
"This is not a case where intervention is automatic. The doctrine of separation of powers will be best served by declining the application at this stage," they said.
The bench ruled that the application by Gachagua is premature as they are being called to anticipate an outcome that's yet to be concluded.
A three-judge bench constituted by Chief Justice Martha Koome on Wednesday declined to stop the Senate trial only hours after Justice Chacha Mwita also gave a similar ruling.
With all his attempts to block the impeachment through the courts exhausted, Gachagua's focus now turns to the Senate to defend himself.
Last week, MPs voted overwhelmingly in favour of removing the deputy president over 11 charges including accusations of corruption.
Gachagua is accused of practising ethnically divisive politics and undermining the government.
The DP is accused of acquiring properties through corrupt means, but Gachagua has fought back saying most of the houses and land belonged to his late brother's estate.
The 59-year-old politician, popularly known as “Riggy G”, has described allegations against him as "outrageous" and "sheer propaganda".