(Adds Varadkar says believes Johnson will compromise; level-playing field key) DUBLIN, Dec 9 (Reuters) - Ireland’s Deputy Prime Minister Leo Varadkar said on Wednesday he believed it was possible that Britain and the European Union will secure a post-Brexit trade deal in the coming days and put the chances of success at around 50%. “Ultimately it takes a little bit of politics at the end and both sides to move a little bit at the end. But I think that is possible,” Varadkar, a significant player in earlier Brexit talks when he was prime minister, told RTE radio. He said he thought Irish Prime Minister Micheal Martin’s assessment that the chances of a deal were 50-50 was “absolutely correct” and pointed to so-called “level playing field” rules to prevent Britain undercutting EU standards on things like labour and environmental standards as key to a deal. “Is (British Prime Minister) Boris Johnson willing to make concessions in those areas? I think he probably is...I think his natural instincts are actually much closer to the more liberal London mayor that he was than the more conservative Brexiteer,” Varadkar said, referring to Johnson’s 2008-2016 mayoral term. “I think any set...of level playing field rules would have to be ones that the UK wouldn’t feel are imposed on them,” Varadkar said. “That is where the sovereignty piece comes in and that will be a circle that will be hard to square.”