If you want a glimpse of how competitive the fight to take over the U.S. House has become in 2018, just turn on the TV.

Driving the news: Democrats and Republicans have spent nearly $40 million on more than 128,000 Congressional campaign ads through June 11, up 54% from the same period in 2014, Bloomberg reports.

Why it matters: There's a lot at stake for both parties this year, as they fight for the House majority in President Trump's first midterm election. Increased advertising and ad spending is a good indicator of which races are truly the most competitive.

By the numbers: Kantar Media, the political advertising tracking group behind Bloomberg's data, estimates that $2.4 billion will be spent on broadcast TV ads for races at all levels during the 2018 election cycle (that's 14% more than 2014 ad spend).

• Campaign ads for House races have been broadcast in 112 of the country's 210 TV markets.
• Kantar Media estimated spending will reach $850 million on local cable TV ads and $600 million for Internet ads.
• The Congressional Leadership Fund has reserved $50 million for broadcast and cable ads in the coming months. Democratic groups will likely match this number or get close to it.

Be smart: Advertising will ramp up aggressively in the weeks leading up to the election, when both parties are hoping to snag last-minute undecided voters and encourage their base voters to actually show up to the polls.