* Charles Sousa is former RBC banker, cabinet minister
* Seen sticking with 2017-18 target for balanced budget
* Swearing-in ceremony at 3 pm ET on Monday
By Claire Sibonney
TORONTO, Feb 11 (Reuters) - Ontario's incoming Liberal premier Kathleen Wynne has chosen former banker and cabinet minister Charles Sousa to become the province's next finance minister, according to media reports.
Wynne's office declined to confirm the reports and said the official announcement would not be made until later on Monday.
But the selection of her former leadership rival Sousa for the high-profile portfolio was widely expected, especially after Sousa endorsed Wynne at the party's leadership convention last month.
Wynne, who will be sworn in to replace Dalton McGuinty around 3 p.m. (2000 GMT), is set to become Ontario's first female leader, and the country's first openly gay premier.
Sousa worked at the Royal Bank of Canada for more than 20 years before entering politics. He served under McGuinty as the provincial minister of immigration. He also held the labor portfolio and was the minister in charge of the 2015 Pan American Games.
The new finance minister is expected to stick to the government's existing budget plan, designed to eliminate the province's deficit by the 2017-18 fiscal year.
Sousa, 54, replaces Dwight Duncan, the former deputy premier who has been finance minister for the last seven years.
Sousa's first major challenges will be crafting the upcoming 2013-14 budget - expected in the spring - and getting it passed through the minority legislature.
The centrist Liberals need support from at least one of the opposition parties, the left-leaning New Democrats or the right-wing Conservatives, in order to avoid a snap election and stay in power.
The Liberals said last month they expect an C$11.9 billion ($11.88 billion) budget deficit in 2012-13. The province has been under pressure from ratings agencies and was downgraded by Moody's last year.
The government responded with a pledge to curb spending growth, which has led to conflicts with teachers and other unionized workers in the province.
Ontario accounts for roughly 40 percent of Canadian gross domestic product and is among the largest sub-national borrowers in the world, issuing bonds worth nearly C$35 billion in 2012.