As head of the Communist Party of Latvia in 1991 he opposed Latvia's independence from the Soviet Union and issued a list of Latvian pro-independence politicians to be arrested but on 23 August 1991 was imprisoned himself[2] for his role in attempting to overthrow the then new democratic government and supporting the August 1991 coup d'état attempt in Moscow.

[3][4] Despite his incarceration, Rubiks was nominated as a candidate in the 1996 Latvian presidential election by the Socialist Party, but lost to incumbent Guntis Ulmanis.

In a 2000 poll, Rubiks was ranked the least popular politician in Latvia with a score of -22.4 points.

[8] In 2012, Rubiks distributed his biography "From Political Prisoner to European Parliament Member" to all EP members, drawing criticism from other MEPs from Latvia for the claims made in the book.

[9] In 2015, after the Socialist Party of Latvia lost in the 2014 European Parliament election, he resigned as its chairman.