She has been a deputy to the Assembly of the Republic representing the Portuguese Communist Party (PCP) in the Setúbal constituency since 2009.

[2] Paula Alexandra Sobral Guerreiro Santos Barbosa was born on 29 September 1980 in the Portuguese capital of Lisbon, but has lived in Seixal in the Setúbal District all her life.

[2][4] In the XI Legislature (2009–2011) she worked on the parliamentary committees on Environment, Spatial Planning and Local Power; Foreign Affairs and Portuguese Communities; and Health.

In the XII Legislature (2011–2015) she remained on those committees and was active on several health-related working groups, including those on death certificates; non-conventional therapeutics; medically assisted procreation; palliative care; and alcohol and drug addiction.

[5][6][7] On 21 April 2022, after the president of Ukraine, Volodymyr Zelensky, addressed the Assembly of the Republic by teleconference during the Russian invasion of his country, Santos said that his speech "served to encourage confrontation, clearly visible in the call for more weapons and sanctions".