WASHINGTON - U.S. President Donald Trump on Tuesday stepped up his accusations against Google, claiming without offering evidence that the technology company worked to subvert his 2016 presidential campaign and warning he was watching it “very closely” ahead of the 2020 election. Trump, in a series of early posts on Twitter, also slammed Google’s Chief Executive Officer Sundar Pichai, and again raised questions about the search engine’s work with China, despite his administration’s earlier comments that any such work was limited. “We go to great lengths to build our products and enforce our policies in ways that don’t take political leanings into account,” a Google spokesperson said in email statement. Trump, who is seeking re-election in 2020, has repeatedly slammed Google and a host of other technology companies, echoing conservative critics’ claims of unfair treatment and raising the spectre of regulation.