[1] The party contested the 2004 legislative elections, mustering 201,396 votes nationwide (1.58%).

[2] The Supreme Court declared TUCP, as well as a few other party-list organizations, as winners in the 2007 legislative elections by virtue of the Philippine Constitution.

Mendoza was one of the principal authors of landmark legislation: Pantawid Pamilyang Pilipino Program (4Ps) Act which institutionalizes 4Ps as a national poverty reduction strategy;[4] the Magna Carta of the Poor that guarantees the rights of the poor and establishes the necessary government interventions for poverty alleviation,[5] and the Department of Migrant Workers (DMW) Act which establishes the DMW as the single home for all the needs and concerns of the Overseas Filipino Workers (OFWs).

[6] He is also pushing for the passage of the Security of Tenure Bill which seeks to end the prevalent and abusive practice of labor-only contracting.

He was also a member of the Philippine delegation to the 36th ASEAN Inter-Parliamentary Assembly (AIPA) General Assembly held in Kuala Lumpur, Malaysia in September 2015 and to the 24th Association of Southeast Asian Nations (ASEAN) Summit and the 10th Brunei Darussalam–Indonesia–Malaysia–Philippines East ASEAN Growth Area (BIMP-EAGA) Summit in Nay Pyi Taw, Myanmar in May 2014.