Wales has been “held back” and has not been able to fulfil the potential offered by devolution, Plaid Cymru leader Leanne Wood said.
In her keynote speech at the party’s conference in Caernarfon, Ms Wood vowed to win the trust of voters to build a “new Wales”.
Plaid Cymru gained an extra Westminster seat in the general election but saw its vote share drop, with Ms Wood highlighting the “presidential nature” of Theresa May’s campaign and the “two-party polarisation” that resulted from it.
But she insisted she would lead the party into the Welsh elections in 2021 which presented an opportunity for political change and the chance to “push to govern ourselves”.
Ms Wood said: “Through my involvement in politics, I’ve been aware of how Wales has been held back, and how for many people this has meant low pay, emigration, bad housing and an NHS under constant pressure.
“After being governed from afar by people who were out of touch with people’s lives in this country, it was a real breakthrough to win that Yes vote for Wales back in 1997.
“But 20 years on, our country hasn’t fulfilled its potential.”
The case for more powers in Cardiff Bay is “incontrovertible”and “our campaign to lead the Welsh Government in 2021 has to go hand in hand with a push to govern ourselves”.
In an apparent acknowledgement that voters may not be ready for more upheaval, Ms Wood said: “To the citizens of Wales, I want to say that I accept that we need to earn your trust. You have just voted in the most dramatic election for decades.”
But Plaid Cymru has “the ideas and ambition to show a new way for Wales” and “we will prove to you that we have what it takes, together”.
Ms Wood used her speech to condemn the “frightening scenes” in Spain in response to Catalonia’s bid for independence, comparing the reaction to “Franco’s days of fascism”.
She also vowed not to give up the fight to remain in the European single market and customs union and said Plaid would “watch the unfolding Brexit process like hawks”.