Some 200 new senators recently endorsed by the Election Commission (EC) have the task of selecting a Senate Speaker, a position crucial for the integrity of the upper house.
This initial task will test whether accusations of cronyism influencing these new senators hold any truth.
The recent Senate election process has been criticised for being influenced by the Bhumjaithai Party, a key coalition government partner, and its associates.
Although the BJT has denied the allegation, and it is difficult to substantiate such a claim, the upcoming vote for the Senate Speaker this week might prove whether such an allegation has grounds.
So far, at least three senators-elect have emerged as potential candidates for the post. They are ex-4th Army chief Gen Kriangkrai Srirak, former Buri Ram governor Mongkol Surasajja, and former career judge Boonsong Noisophon.
Gen Kriangkrai and Mr Mongkol are said to have close ties with the Bhumjaithai Party or its key figures.
Gen Kriangkrai, who received the most votes in Group 1, representing state administration and national security careers, is known to have close ties to BJT leader and Interior Minister Anutin Charnvirakul, as they were classmates at the Thai National Defence College.
Mr Mongkol, meanwhile, is known to have connections with a powerful "Ban Yai" (big house) political family in the northeastern province of Buri Ram, a stronghold of the Bhumjaithai Party.
He is said to have close ties with Newin Chidchob, a former veteran politician and co-founder of the Bhumjaithai Party. Mr Mongkol applied to run for a Senate seat in Buri Ram.
Mr Boonsong, the third potential candidate, has a robust legal background. He is a former EC member and court judge.
He began his legal career as a prosecutor before becoming a judge and has held several important positions at the Courts of Justice, including President of the Court of Appeal Region 7 and judge at the Supreme Court.
Mr Boonsong is said to be backed by a group of about 30 new senators calling themselves "independent senators" in his bid to become Senate Speaker.
The Senate is crucial for scrutinising draft laws sponsored by the government and other organisations, and for appointing various important "independent organisations", including anti-graft agencies, the Ombudsman, Constitutional Court judges, the Election Commissioners and members of the State Audit Commission. So, the independence and qualifications of the Senate Speaker are vital.
For a functioning democracy, the Senate must prevent the executive branch from exerting undue control over legislative proceedings, thereby safeguarding the principle of checks and balances within the political system.
Although political cooperation must be sought to ensure that important tasks can progress and be completed, the independence of the Senate Speaker from the government or political groups is crucial, as is their legal knowledge.
Amid reports of "block voting" and lobbying in the Senate Speaker election, this will be the first test for the new 200 seat-Senate.
Regardless of the political accusations, the new Upper Chamber will send a message about its true colours. The outcome will either restore faith in the Senate's integrity or confirm fears of entrenched political manipulation.