Florida’s U.S. Senate race remains close, but new internal research from the Senate Majority PAC suggests there is still an opportunity for Rep. Patrick Murphy to grow his share of the votes.

Internal polling done by Civis Analytics shows the race between Murphy and Sen. Marco Rubio is a statistical tie. Murphy leads 45 percent to 44 percent, with 9 percent undecided.

Civis Analytics, however, expects “undecided voters in the survey to break toward Murphy, and allocating these voters grows Murphy’s lead to 51.6 versus 48.4 for Rubio.” According to a Civis Analytics memo, the organization also said there is a “substantial opportunity to grow Murphy’s vote share” as voters become more familiar with candidates the closer Election Day gets.

“Patrick Murphy is tied with Rubio despite running behind Democratic benchmarks among several key groups (Democrats, non-white voters and Millennials),” according to Civis Analytics memo. “Murphy’s support is buoyed by running ahead of Democratic benchmarks among older, white, and more conservative voters. In short, Murphy has a lot of room for growth.”

Rubio, on the other hand, appears to be running behind among “traditional parts of the Republican coalition in the state.” The Civis research noted Rubio’s favorability dropped over the summer and said his support is “inflated by his temporary advantage in name ID.”

The research found Rubio is “winning voters who haven’t heard of Murphy by 2-to-1.”

Civis Analytics surveyed 1,463 people from a sample of representative voters from Aug. 9 through Aug. 15. The company reached Floridians on both landlines and cell phones, and the survey had a margin of error of 2.8 percent.

Rubio and Murphy are headed into a tough general election, with most recent polling showing a close race in November. The two men have already been attacking each other, and the attacks will likely get worse as Election Day nears.

The race is one of several closely watched races across the country, and could be key to determining control of the U.S. Senate. Outside groups have already committed to spending a substantial sum in Florida, with the Senate Majority PAC hitting the airwaves during the primary to help Murphy.

In May, the Senate Majority PAC — a super PAC that aims to get a Democratic majority in the Senate — announced it had reserved $10.5 million in TV time in Florida this fall. At the time, Morning Consult reported the super PAC had also reserved time in New Hampshire, Nevada and Ohio.

According to the Civis Analytics report, prepared for Senate Majority PAC, Murphy is poised to perform well come November.

“Rubio is already a well-known candidate in the state and is likely at his ceiling,” the memo said. “In contrast, Murphy has room to grow among several Democratic-leaning groups that should be responsive to communications. He is well positioned to win this seat in the fall.”