New York: Kendrick Lamar, one of the most praised voices in hip-hop, took on both US President Donald Trump and rivals in the rap world in a surprise new song.The California rapper ended the track by throwing out the date April 7 — leading fans to expect more music, and perhaps even his next album, on that date. Lamar late Thursday dropped “The Heart Part 4,” a nearly five-minute track of rapid-fire rhyme that, in contrast to his often eclectic musical influences, is led by an unadorned bass line. The Grammy-winning artist — whose 2015 album “To Pimp a Butterfly” was quickly hailed as a classic — paints a bleak picture on his latest track, rapping: “The whole world goin’ mad.” “Donald Trump is a chump / Know how we feel, punk / Tell ’em that God comin’ / And Russia need a replay button, y’all up to something,” he raps, referring to the Trump presidential campaign’s alleged ties with Russia. Lamar also points to Trump’s failure to win the popular vote in last year’s election, rapping: “America’s truth ain’t ignoring the votes.” Lamar has been an active social commentator. His “Alright” became an unofficial anthem of the Black Lives Matter movement, while another “To Pimp a Butterfly” track — “How Much a Dollar Cost,” about an encounter with a beggar in South Africa — was hailed by then-president Barack Obama as his favourite song of 2015. More unusually for the 29-year-old Lamar, much of “The Heart Part 4” is about boasting of his own status in hip-hop.“30 million later, my future favours / The legendary status of a hip-hop rhyme saviour,” he raps, exalting both his earnings and his skill. In several cryptic verses in the song, Lamar appears to take shots at other rappers — especially Drake, the Toronto superstar, whom he suggests is overrated. “The Heart Part 4” is loosely inspired by funk legend James Brown’s “Don’t Tell a Lie About Me and I Won’t Tell the Truth On You,” off his 1974 double-album “Hell.” If Lamar releases new music on April 7, it would come little more than a week before he is one of the headliners of Coachella, the premier music festival in California.