In a clear signal aimed at addressing UK concerns over European free movement laws, the Polish prime minister, who was unanimously appointed by EU heads of state and government during a summit in Brussels on Saturday, said, "many of [David Cameron's] suggestions put forward for EU reform are sensible, we can work together to eliminate any welfare abuse by EU migrants".
The UK's Daily Telegraph reported that Tusk had managed to reassure and win over Cameron following a telephone call between the two premiers last week, where, "crucially, the Polish premier indicated he would be ready to support Cameron's plans to introduce new limits on welfare payment to migrant workers from other EU states".
Limiting the access of EU migrants to UK social security payments is a key EU reform platform for Cameron, both on the European and national political stages.
"The EU, and I personally, will certainly meet the concerns voiced by Britain" - Newly elected European council president Donald Tusk
Tackling the issue of so-called benefits tourism is a favourite subject of the British tabloid press and has helped fuel a rise in Euroscepticism among traditional Conservative voters ahead of next year's UK general elections.
Cameron hopes that having a sympathetic ear at the heart of the EU will help overcome accusations - especially following his recent failure to block the appointment of Jean-Claude Juncker as new commission president - that the UK has little influence in Brussels.
The Tory leader also had talks with Juncker over the weekend in the hope of securing a "strong economic portfolio" for the UK's commission nominee Jonathan Hill.
The appointment of Tusk as council president and Italian foreign minister Federica Mogherini as the EU's new foreign affairs chief paves the way for Juncker to begin the complex process of distributing portfolios.
The allocation of a high-profile post within Juncker's new college of commissioners would also signal to Cameron's critics that Brussels is now taking British concerns seriously, allowing the embattled prime minister to start promoting a narrative along the lines that winning reforms and staying in the EU would be preferable to a full British exit.
"I'm delighted with what Donald Tusk has said about the importance of reform in the EU and addressing the concern that Britain has in the EU" - UK prime minister David Cameron
Tusk's comments, immediately following his appointment, that, "The EU, and I personally, will certainly meet the concerns voiced by Britain," and that, "no one reasonable can imagine the EU without Britain", were warmly welcomed by Cameron.
"I'm delighted with what Donald Tusk has said about the importance of reform in the EU and addressing the concern that Britain has in the EU," Cameron told journalists at the end of the summit.