Joe Zidle has one piece of advice to investors: Ignore the drama coming out of Washington.

In a week that saw the ousting of key figures in the Trump administration, Zidle, a portfolio strategist for Richard Bernstein Advisors, says investors should keep their cool about what they see in D.C. and focus on market fundamentals instead.

Earnings growth, according to Zidle, has been the biggest driver of the rally, with earnings for the second quarter coming in more than 5 percent above estimates so far.

"We had a growth scare earlier in the year when [investors] thought we'd run into all these policy headwinds, and therefore growth would slow," Zidle said Tuesday on CNBC's "Futures Now." "The key point they missed is that you don't price stocks according to what's happening inside the Beltway."

In fact, Zidle argues that "February 11 of 2016 was far more important than November 8." According to the strategist, February 2016 was when earnings, inflation expectations and oil prices troughed, setting the stage for the start of a new period of expansion. Since February 11 of last year, the S&P has soared 35 percent, a rally that Zidle said can't actually be attributed to politics.

"People wanted to attribute that to the 'Trump bump' or the Hillary relief rally, but the reality is the underlying fundamentals have continued to improve, and I think that's the real story," Zidle says.

On Wednesday, markets continued to rally with the Dow crossing the 22,000 mark, thanks to Boeing and a solid earnings report from Apple. The S&P and Nasdaq, however, moved lower for the fourth time in five sessions.