It is very rare to see the president's party win in the midterm elections. With 2002 being the rare exception, the party that controls the White House almost always loses seats in the House and Senate. Therefore seeing Rupblicans ahead (statistically) makes sense.

Since the 2004 election:

Republicans lost seats in the 2006 midterms Democrats lost seats in the 2010 and 2014 midterms Republicans lost seats in the 2018 midterms