While Arizona and Florida have been getting all the attention for their Senate races, the one shaping up in Indiana is just as crucial since it features a sitting Democrat incumbent locked in a very tight race in a state Trump won by 19 points in 2016. Incumbent Democrat Joe Donnelly holds a slight lead right now over Republican challenger Mike Braun, but analysts expect the race to tighten significantly in coming weeks.

CNBC reports from the Hoosier State on what’s going down with the Donelly versus Braun battle now that the primaries have all been settled:

Centrist Democrat Joe Donnelly holds a narrow edge over Mike Braun, a Republican businessman backed by President Donald Trump, in the crucial Indiana Senate race, according to a new NBC News/Marist poll.

The survey, released Wednesday, said 44 percent of likely voters support Donnelly, compared with 41 percent backing Braun in a three-way race. A Libertarian candidate, Lucy Brenton, gets the support of 8 percent.

In a head-to-head contest, Donnelly leads Braun 49 percent to 43 percent, just outside the 5 percent margin of error for likely voters. Among registered voters, the Democrat has the support of 48 percent, compared with the Republican’s 42 percent.

Republicans see Indiana as one of their best opportunities to flip a Democratic seat as they try to keep or expand their 51-49 majority in the Senate. Trump carried the Hoosier State by nearly 20 percentage points in 2016, while Donnelly won his seat in 2012 by about 6 percentage points.

Polling has been sparse, but Indiana is one of the most hotly contested Senate races this year. Trump and national Republican and Democratic groups have already gotten heavily involved.

As the story notes, there is a libertarian in the race, Lucy Brenton, currently taking upwards of 8% of the vote according to polls. Brenton’s support won’t be that high come Election Day, third parties never are, but a few percent could easily sway a close race.

Just a week ago, the President held a campaign rally for Braun in Evansville, Indiana:

Indiana is a state where Republicans think Trump’s presence can help considering he won the state by almost 20 points. Donelly, for his part, has been a “red state Democrat” in that he hasn’t strayed too far into progressive politics since far left candidates don’t stand much of a chance in Indiana. Similar to the success of Democratic Sen. Bill Nelson in Florida, Donelly has stayed quiet on controversial matters and typically rides a center-left line of most policies.

The polling is sparse right now, and shows a lead for Donnelly:

Indiana Senate Braun vs Donnelly Polls

Seems like those numbers would indicate Donnelly is in a good position, but they largely reflect a lack of polling and general lack of interest during the summer months. Braun is also fairly unknown which means as his recognition rises, his polling numbers will follow.

Donelly is a first-term Senator, he took the office in 2012 so this is his first re-election campaign. He rode in on the coattails of Barack Obama and a bad Republican challenger last time around. This year, however, Braun is formidable, and Donelly is going to have a tougher race in 2018 without Obama on the ballot.

Republicans see this seat as winnable since Indiana leads solidly red and Republicans, if they come out for Braun, may be able to overcome any blue wave simply by sheer demographics alone.