Donald Tusk is visiting Canada and a spokesman for Harper says the economy will be the focus of their discussion.
The two men are also expected to discuss the negotiations over a free trade deal between Canada and the European Union.
An Ontario man is begging for Harper to bring up the case of his two children who are now the focus of a battle before the Polish courts.
Stephen Watkins, 40, gained custody of his sons,aged 8 and 10, after he broke up with his wife Edyta Watkins.
She and the boys vanished in 2009, only to emerge later in Poland, the woman’s native country.
A Polish court ruled last year against sending the boys back to Canada and the Newmarket, Ont. man Watkins is appealing that decision -- a hearing is set for Wednesday.