Image copyright WhereIsPaulCook.com Image caption Milk cartons with Paul Cook "missing" advert

Pick up a carton of milk in some parts of the US this week and you might see a Republican politician staring dolefully out at you from the flyer on the side - rather than the usual missing children ads.

Anti-Trump activists have also been paying for billboards, making videos and songs, and posting mock missing person adverts on social media to pressure their representatives to hold town hall meetings.

But after recent public events descended into combative showdowns, some politicians are refusing to expose themselves to what they are say are set-ups by liberal fringe groups.

President Trump has claimed that the angry crowds are being organised by liberal protesters.

Activists in California have gone one further, setting up an entire website, whereispaulcook.com, to try to chase down Representative Paul Cook. They are now planning a "candlelit vigil" to "pray for Paul".

Meanwhile, a group calling themselves "Stop the Speaker" have funded a billboard accusing House Speaker Paul Ryan of running away from voters.

In Martin County, Florida, activists produced a video - a take on the song Dear Future Husband by Meghan Trainor, urging Florida representative Brian Mast to hold a Town Hall meeting. He has since agreed to hold a public event, with a focus on veterans, but the activists are frustrated that it is scheduled for 13:00 on a weekday.

The song's lyrics were penned and performed by Melissa Gardner, a 39-year-old former military intelligence officer and Fulbright scholar. She told the BBC she is registered as Republican party member, but voted for Hillary Clinton as she disagrees with the direction Mr Trump is taking.

She is part of Indivisible, a network established to challenge Donald Trump's agenda in the wake of his electoral victory.

With former Congressional workers among its founders, the group has created an activism guidebook, including advice for disrupting scheduled events to "shift attention to your own message".

They say their strategies are modelled on those of the Tea Party wing of the Republican party. Ms Gardner says that for her, and many others involved locally, it is her first foray into political activism.

The network is also behind whereispaulcook.com. Warehouse worker Jason Graham, 44, is one of the website's organisers. He too says he is new to political activism, and says his 60-strong local chapter contains mainly Democrat voters, but also anti-Trump Republicans, libertarians and Greens.

"Most are people who have really never paid much attention to politics before," he says.

He says his group are not aiming to be confrontational, they just want a town hall meeting to "put questions in a public setting".

The Democratic advocacy group MoveOn.org, which powerfully backed Barack Obama's presidential campaign, is also involved. It has dubbed this week "Resistance Recess" - a reference to the congressional break when lawmakers are expected to return to their home constituencies.

MoveOn.org has published guides and tips for activism, including "bird dogging" - which it defines as challenging representatives doggedly at public events, though one of the training videos admits can be considered "heckling".

Strategies include spreading sympathetic people out through the audience and recording video to put on social media. The group also suggests posting the "missing" adverts to pressure lawmakers into holding public meetings.

Image copyright AP Image caption Rep Chaffetz said audience behaviour was 'intended to bully and intimidate' at his town hall event

Republicans have dismissed the town hall meetings as engineered, unrepresentative attempts to cause chaos. Rep Paul Cook's office told local media he prefers other means to communicate with constituents, as town halls "reward the most disruptive and loudest voices".

"The main local agitators demanding a town hall seek not a dialogue but a platform to espouse an extreme political agenda that was resoundingly rejected," the office was quoted as saying.

Rep. Jason Chaffetz said behaviour at an event he hosted in February was "intended to bully and intimidate".

White House Press Secretary Sean Spicer has said such meetings have contained "a bit of professional, manufactured protest", and that a "very paid, 'astroturf' [in contrast to grassroots] type movement" is developing..

On Thursday, the former Democratic Congresswoman Gabrielle Giffords weighed in, after Texas representative Louie Gohmert cited her shooting at a 2011 outdoor political meeting as a reason for not appearing in person.

Ms Giffords tweeted: "To the politicians who have abandoned their civic obligations, I say this: Have some courage. Face your constituents. Hold town halls.

"I was shot on a Saturday morning. By Monday morning my offices were open to the public."