WASHINGTON (Reuters) - For some Democrats, Donald Trump may seem to be a gift - set to steer Republicans into a trainwreck election in November - but senior Democrat Harry Reid said on Thursday he worried people might be too confident.  “Am I concerned about it? Of course I am,” the U.S. Senate Democratic leader said in a conference call with reporters.  “I think this race could be a debacle for the Republicans,” Reid added. “But I’m not taking anything for granted. I’m not being over confident.” Trump effectively clinched the Republican presidential nomination for the Nov. 8 election this week after a primary battle that angered many - including in his own party’s establishment - for his bombastic style and proposals such as building a wall along the southern U.S. border to keep out Mexicans.  Some Democrats believe that divisive style makes him an easier opponent than some of the other 16 Republicans who started out in the race. Trump’s Democratic opponent will likely be former Secretary of State Hillary Clinton. Reid, who is retiring from the Senate after this year, used his position as the Senate’s Democratic leader in 2012 to aggressively attack then-Republican presidential candidate Mitt Romney. During a teleconference to discuss Trump and Republican opposition to Supreme Court nominee Merrick Garland, Reid made clear that he will perform in a similar role against Trump. “By nominating Trump, I guess it’s the natural evolution of a party that’s spent eight years defining itself entirely on what it’s against: anti-immigrant, anti-woman,...anti-Obama, anti-working people,” said the senator from Nevada. Reid, who has called Trump a “monster,” said there should be a closer look at Trump’s business dealings and called on the real estate developer to open up his tax records. Reid recalled some of his own campaigns in his political career that were lost or won by razor-thin margins, adding, “I can speak from personal experience. You cannot be over-confident.” 
Not over yet: Reid cautions Democrats relishing Trump election battle