A new morning consult poll gives the former vice president, Joe Biden, a 13-point lead over Republican President Donald Trump. The former governor, John Hickenlooper, has less than half that advantage against incumbent Cory Gardner in the U.S. Senate race.

The poll, released Tuesday morning, has a margin of error of plus or minus 4 points, based on polling 616 likely voters in Colorado.

Though it’s difficult to draw conclusions from a single poll, compared to previous polls, it shows a tightening race, as Gardner only begins to formally campaign.

The full poll from Morning Consult is available by clicking here.

While Biden led Trump 52% to 39%, Hickenlooper led Gardner 46% to 42%, with 5% favoring another candidate in the Senate race and 6% who said they didn’t know or had no opinion. The survey was conducted July 17-26.

A year ago, in-state polling indicated the Republican incumbent senator was popular than Trump, with a 40% approval rating to the president’s 43%, long before Democrats settled on a nominee.

In the waning days of the primary, Hickenlooper weathered perhaps the roughest period on his popularity of his 17-year political career, including his days as Denver’s mayor before two terms as governor. Hickenlooper was cited for two violations and a contempt charge in June for failing to answer a subpoena by the state Independent Ethics Commission looking into luxury travel he accepted as governor. Hickenlooper sought to characterize the complaints against him, led by Republicans, as frivolous.

Hickenlooper got it the Senate race after dropping out of the presidential race, when he said he was interested in the Senate race and didn’t think he would be a good senator. His presidential ambitions never took hold, and he joined a crowded field of Democrats for the chance to take on Gardner last fall.

In previous polls, the first-term senator from Yuma was less popular than the president he has sided with health care, environmental regulations, impeachment and other issues that have solidified Trump’s support from Republicans.

“He’s got my complete and total support and endorsement,” Trump said of Gardner at a rally in Colorado Springs in February. “He will never let you down.”

During the 2016 race, Gardner called Trump a “buffoon.”

A Colorado poll last October showed an 11-point edge for pursuing Trump’s impeachment, which the Democratic-led House eventually imposed before the Republican-led Senate voted to acquit.

Last fall, a poll with a hypothetical Hickenlooper-Gardner matchup gave the former governor a 13-point advantage.

On July 1, Public Policy Polling, working for national Democratic-aligned groups, gave Hickenlooper an 11-point lead, with a 19-point gap among self-described independent voters.