Results Monday from balloting a day earlier for the governorship of Umbria, one of the country's smallest regions, gave a coalition headed by Salvini and including the far-right Brothers of Italy party and former Premier Silvio Berlusconi's center-right Forza Italia party, a combined 57.5 percent of the votes.
Donatella Tesei, a League member and current senator who has served as mayor of a town in Umbria for 10 years, was elected governor. A coalition anchored by the populist 5-Star Movement and the center-left Democratic Party took a trouncing with a combined 37.5 percent.
Since early last month, the 5-Stars and the Democrats have governed Italy in an uneasy alliance of rivals formed by Premier Giuseppe Conte to keep Salvini from power. The Umbria triumph shows that "Italians don't like betrayals," said an elated Salvini.
With the victory in the central region, the anti-migrant League continues to expand its influence southward from its northern power base. Conte insisted the dismal result won't affect his government's viability.
The vote was a "test that shouldn't be ignored at all," Conte told reporters. But "we're here to govern with courage and determination." For sure, the results won't help tensions between the 5-Stars and Democrats, who shelved bitter rivalries in order to govern together. The coalition came to power after a bad miscalculation by Salvini, who bolted from Conte's first coalition, where the League and the Movement had governed for 15 months in a fractious alliance.
Salvini had hoped that by abandoning Conte he'd trigger early elections. But the 5-Stars and the Democrats ganged up on him, shutting him out of power, at least for now. The Umbria outcome gives Salvini fresh momentum, as he plots his comeback nationally.
The League snared 36.9 percent of the vote, a huge jump compared with the 14 percent won in the previous Umbria election, while the Democrats tumbled to 22.3 percent, compared with 35.7 in the last election.
Eclipsing Berlusconi's party as the second-biggest party on the right was Brothers of Italy, which has neo-fascist roots The big losers were 5-Star, taking only 7.4 percent. The Movement's embattled leader, Luigi Di Maio, blamed the defeat on teaming up regionally in Umbria with the Democrats. "This is an experiment that didn't work," he told Sky TG24 TV.
The governor of neighboring Tuscany, Enrico Rossi, warned his fellow Democrats against linking their fate on future campaign trails with the populists. In January, another long-time regional fortress of the left, Emilia Romagna, poses the next big electoral test.
"This last-minute alliance between the 5-Star Movement and the PD (Democratic Party) doesn't work, not even to keep the spread of Salvini at bay," Rossi said.