The three biggest anti-Joe Biden storylines in right-wing media over the last year have either fizzled or are getting less online traction than they used to, according to data from NewsWhip provided exclusively to Axios.

Why it matters: This dynamic has rendered a formidable media ecosystem less effective in boosting President Trump as we move into the heart of the 2020 campaign.

By the numbers: The data shows that for articles published about Biden since last fall by Fox News, Breitbart, Daily Wire, Daily Caller and Western Journal, articles about Biden's mental acuity, Hunter Biden and Burisma, and Tara Reade's sexual assault accusations have generated the most interactions on social media (likes, comments, shares).

But in recent months, that interest has dissipated:

• Engagement on pieces about Biden's mental sharpness peaked in March and then even higher in June, but has decreased since then. Of the three topics, this has gotten the least combined interest.
• Chatter about Hunter Biden serving on the board of a Ukrainian gas company peaked in October, then disappeared by March with a brief spurt in May.
• Interactions on coverage about Tara Reade's allegations against Biden hit a crescendo in late April and early May — reaching a higher peak than any other storyline — before falling away by June.

Overall among these publishers, engagement on all stories about Biden peaked in April and May and has fallen 31% in June and July.

Between the lines: Unlike other storylines that right-wing publishers have feasted on in the past — where new morsels of information reinvigorated news cycles — there have been no new revelations in the Burisma story, and Tara Reade stopped giving press interviews.

• By contrast, the drip-drip of information about Hillary Clinton's email server and the DNC leak fueled news cycles for months during the 2016 campaign.

Yes, but: That dynamic could change any day at the drop of a hat.

The bottom line: This trend underscores Trump's struggle to effectively attack Biden and give him ammunition to turn the focus on his opponent rather than his response to the pandemic.

Our 2020 attention trackeris based on data from NewsWhip exclusively provided to Axios as part of a project that will regularly update throughout the 2020 campaign.

See all past editions of the tracker here.