President Donald Trump arrives aboard Air Force One at Palm Beach International Airport in West Palm Beach, Florida, March 3, 2017. Reuters

President Donald Trump is looking to consolidate his hold over Washington with a Republican supermajority in the Senate that would make it even more difficult for Democrats to block his policies. With critics calling for an independent investigation into his White House and hinting at a future impeachment debate, Trump asked GOP donors Friday to back Republican Senate candidates in the 2018 midterm election to help the GOP reach a 60-seat supermajority.

As Democrats and Republicans alike demand to know more about any ties between the Trump administration and Russia President Vladimir Putin, Trump outlined his vision for his future at the White House while speaking at the Republican National Committee’s spring retreat in Palm Beach, Florida.

"I need you guys to step up and overwhelm them,” the president reportedly said about getting a filibuster-proof Senate majority after the 2018 election, Politico reported.

Republicans now hold 52 seats in the Senate, and are expected to defend nine seats against Democratic rivals in 2018. Meanwhile, 25 Democrats and Independents will be up for election next year and of those, 10 contests will be held in states Trump won in the November presidential election.

It's unclear if Trump can help the GOP win a supermajority in 2018. The president has historically low approval ratings, the lowest of any modern president, and ruling political parties often lose seats in midterm elections when voters want to send a message to an unpopular president.

But Trump doesn't seem worried.

“He was talking about the election, how against all odds he wasn’t supposed to win. I think that was his theme for the night, how he won and won big,” one donor, healthcare executive Mohammad Qazi, told Politico of the spring retreat.

Meanwhile, amid growing questions about multiple people in the White House meeting with Russian officials, including Attorney General Jeff Sessions, Trump went after President Barack Obama Saturday morning on Twitter. "How low has President Obama gone to tapp my phones during the very sacred election process. This is Nixon/Watergate. Bad (or sick) guy!" he wrote.

Democratic U.S. Rep. Brendan Boyle responded with his own tweet: "Don't be distracted by Trump & his lunatic rants. We need an independent investigation into #Trumprussia now."