U.S. Rep. Cheri Bustos, D-Ill., raised $341,700 for the first quarter of this year and was closing in on $1.7 million in the bank, according to new financial filings, a warning sign to any Republican who may be planning to challenge her next year.

Bustos, who is expected to seek a fourth term next year, is on the Republican Party's initial target list for 2018. The Moline Democrat won her race handily last year. But President Donald Trump also narrowly won there and those split districts are where Republicans, at least in this part of the election cycle, are focusing efforts.

The House Democrats' political arm also put Bustos' district on their list to watch in case they need to help out.

Of the $341,700 in contributions, Bustos raised nearly $238,000 from individuals and more than $103,000 from political action committees in the first quarter, which ran from Jan. 1 through March 30.

Financial reports for the quarter were due to the Federal Election Commission this weekend.

Bustos, whose Republican opponent last year had little money, spent far less in the last election cycle than she did in her 2014 race. And because she surpassed more than $3 million in contributions, that allowed her to conserve a lot of money.

Her nearly $1.7 million in the bank is four times what she had in cash on hand at this point in the 2016 election cycle. Two years ago, she had about $419,000 in the bank.

Bustos, who spent much of last election cycle traveling to help other Democratic candidates, had considered a run for governor next year but decided against it. She also has taken a leadership position with the House Democrats, as co-chair of the Democratic Policy and Communications Committee.