It is Europe that will define British politics until the Tories' promised referendum on EU membership is held. Aware of this, Andy Burnham will today become the first of the Labour leadership contenders to visit Brussels. The shadow health secretary will use the trip to woo Labour MEPs (some of whom wield significant influence among party members) and to further outline the stance he would take on the EU (he has already called for the referendum to be held by next autumn).

After the party's collapse in Scotland, following its decision to campaign alongside the Conservatives during the independence referendum (a policy Gordon Brown long warned would lead to ruin), Burnham will announce that he would establish a separate "Labour Yes" campaign for the referendum. His stance will assuage fears, most notably among northern MPs, that Ukip could thrive by framing the party as the Tories' accomplice.

During his meetings with MEPs and the UK Ambassador to the EU, Ivan Rodgers, Burnham will also discuss his renegotiation agenda, including reforms to the EU Posted Workers Directive to strengthen the enforcement of the national minimum wage and address the undercutting of high-skilled labour; action against agencies who recruit exclusively from abroad and deny local workers employment opportunities; and reform of entitlement to in and out of work benefits to reflect the contributory principle.

Burnham said:

Even though Labour is in a leadership campaign, I am not going to let the EU debate be defined by David Cameron. Today, I will discuss with Labour colleagues in the European Parliament what a distinctive pro-European reform package will look like. These are areas that David Cameron will not be focusing on and that is why we be raising them today to make the Labour case for Europe. Re-negotiation cannot be a green light to turn the clock back and weaken employment rights. Labour will also learn the lessons of the Scottish independence referendum and it is my intention to have a separate 'Labour Yes' campaign.

But already there are signs of tensions within Labour over the referendum, with pro-Europeans fearing the party will shy away from full-throated support for EU membership. The shadow Europe minister Pat McFadden writes in the new issue of Progress magazine: "There is no doubt that the way we argued our referendum case was an issue on the doorstep in Scotland, though the troubles of Scottish Labour go deeper than that. The Scottish National party had been running Scotland for years and already held a majority in the Scottish parliament.

"So let us debate how we shape our argument and if learning from the Scottish experience points to a more distinct Labour yes campaign then we should establish that. But there is a difference between campaign tactics and holding to our strategic position.

"We could not have opted out of the argument to maintain the UK. We are not a nationalist party."