UPDATE 1-Croat president mandates Kosor to form government

* Kosor gets mandate to form government

* Speaker expects parliament to vote on Monday

* Budget revision and EU impasse seen as key challenges

By Zoran Radosavljevic

ZAGREB, July 3 (Reuters) - Croatian President Stjepan Mesic mandated former Deputy Prime Minister Jadranka Kosor on Friday to form a new centre-right coalition government after Prime Minister Ivo Sanader unexpectedly stepped down this week.

If approved by parliament, Kosor's first task will be to enforce a set of deep budget cuts, needed to anchor the public finances at a time of a serious economic downturn, and revive the stalled European Union accession talks.

Analysts said the budget revision will be a key test for the new government -- which is not likely to differ much from Sanader's cabinet, which had planned it for mid-July or early September.

"She has submitted proof that she has a parliamentary majority and, after consulting with all the parties, I have given her the mandate," Mesic said.