Japan Prime Minister Shinzo Abe's first politically risky step of declaring the country's intent to join talks on a U.S.-led Pacific Rim free trade pact appears to be paying off as his record high ratings edge even higher.

Public opinion surveys showed on Monday that Abe's support ratings had risen since last month to reach the highest levels since he took office in December and a majority backed Friday's announcement that Japan wanted to join Trans-Pacific Partnership (TPP) membership talks.

The decision launches the "third arrow" in Abe's policy triad following the fiscal pump priming and hyper-easy monetary measures he has pushed since returning to office in December after his Liberal Democratic Party's (LDP) big election win.

While "Abenomics" has been playing to rave reviews in the Tokyo stock market and with voters, business executives and economists say its lasting success hinges on whether and how Abe tackles thorny reforms such as deregulation.

Japan's TPP participation is one such thorny issue and serves as the first test of Abe's ability to navigate the political minefield to get there.

Proponents say the trade pact will help tap vibrant regional growth and act as a catalyst for reforms such as deregulation. However, it is staunchly opposed by the powerful farm lobby, which has long served as the LDP's power base.

Two of Abe's predecessors from the now-opposition Democratic Party of Japan promoted the idea of joining TPP when they were in government, but stumbled over divisions within their own party.